[SPARK-4982][DOC] `spark.ui.retainedJobs` description is wrong in Spark UI configuration guide
[SPARK-4982][DOC] `spark.ui.retainedJobs` description is wrong in Spark UI configuration guide

Author: wangxiaojing <u9jing@gmail.com>

Closes #3818 from wangxiaojing/SPARK-4982 and squashes the following commits:

fe2ad5f [wangxiaojing] change stages to jobs

guoxiaolongzte/spark,alunarbeach/spark,rednaxelafx/apache-spark,alunarbeach/spark,byakuinss/spark,techaddict/spark,lxsmnv/spark,rednaxelafx/apache-spark,ahnqirage/spark,UndeadBaneGitHub/spark,patrick-nicholson/spark,sahilTakiar/spark,akopich/spark,kiszk/spark,ibm-research-ireland/sparkoscope,xflin/spark,rekhajoshm/spark,zero323/spark,joseph-torres/spark,poffuomo/spark,icexelloss/spark,zhouyejoe/spark,map222/spark,bOOm-X/spark,mdespriee/spark,zero323/spark,Panos-Bletsos/spark-cost-model-optimizer,ajaysaini725/spark,WeichenXu123/spark,bravo-zhang/spark,debugger87/spark,MLnick/spark,chuckchen/spark,Aegeaner/spark,dongjoon-hyun/spark,hvanhovell/spark,saltstar/spark,chuckchen/spark,SHASHANKB/spark,ueshin/apache-spark,apache/spark,tejasapatil/spark,markhamstra/spark,ueshin/apache-spark,ajaysaini725/spark,icexelloss/spark,kimoonkim/spark,big-pegasus/spark,jlopezmalla/spark,aray/spark,hvanhovell/spark,ericvandenbergfb/spark,pgandhi999/spark,holdenk/spark,bravo-zhang/spark,metamx/spark,ron8hu/spark,SnappyDataInc/spark,ptkool/spark,guoxiaolongzte/spark,andrewor14/spark,eyalfa/spark,szhem/spark,actuaryzhang/spark,Aegeaner/spark,apache-spark-on-k8s/spark,someorz/spark,Panos-Bletsos/spark-cost-model-optimizer,aray/spark,mike0sv/spark,Panos-Bletsos/spark-cost-model-optimizer,bravo-zhang/spark,rekhajoshm/spark,joseph-torres/spark,tejasapatil/spark,metamx/spark,alunarbeach/spark,panfengfeng/spark,andrewor14/iolap,Panos-Bletsos/spark-cost-model-optimizer,nlalevee/spark,zzcclp/spark,wangyum/spark,ConeyLiu/spark,wangmiao1981/spark,zuotingbing/spark,kevinyu98/spark,liyichao/spark,xflin/spark,hvanhovell/spark,UndeadBaneGitHub/spark,adrian-ionescu/apache-spark,publicRoman/spark,srowen/spark,dhruve/spark,sureshthalamati/spark,JoshRosen/spark,jiangxb1987/spark,ioana-delaney/spark,sachintyagi22/spark,markhamstra/spark,aosagie/spark,brad-kaiser/spark,ron8hu/spark,szhem/spark,HyukjinKwon/spark,JoshRosen/spark,aosagie/spark,dhruve/spark,nilsgrabbert/spark,aosagie/spark,WeichenXu123/spark,xuanyuanking/spark,gioenn/xSpark,facaiy/spark,dhruve/spark,pronix/spark,setjet/spark,cin/spark,rikima/spark,michalsenkyr/spark,alunarbeach/spark,apache-spark-on-k8s/spark,bravo-zhang/spark,cin/spark,taroplus/spark,gioenn/xSpark,Panos-Bletsos/spark-cost-model-optimizer,mike0sv/spark,joseph-torres/spark,aosagie/spark,liutang123/spark,caneGuy/spark,janewangfb/spark,cloud-fan/spark,kevinyu98/spark,brad-kaiser/spark,nilsgrabbert/spark,someorz/spark,guoxiaolongzte/spark,sureshthalamati/spark,spark-test/spark,jiangxb1987/spark,saltstar/spark,gioenn/xSpark,minixalpha/spark,haowu80s/spark,yanboliang/spark,highfei2011/spark,darionyaphet/spark,WeichenXu123/spark,dbtsai/spark,liyichao/spark,rekhajoshm/spark,ptkool/spark,liyichao/spark,mahak/spark,actuaryzhang/spark,shuangshuangwang/spark,ajaysaini725/spark,patrick-nicholson/spark,ahnqirage/spark,joseph-torres/spark,patrick-nicholson/spark,UndeadBaneGitHub/spark,spark-test/spark,loneknightpy/spark,shubhamchopra/spark,pronix/spark,eyalfa/spark,pgandhi999/spark,jlopezmalla/spark,ahnqirage/spark,publicRoman/spark,shubhamchopra/spark,SHASHANKB/spark,jrshust/spark,brad-kaiser/spark,darionyaphet/spark,ericvandenbergfb/spark,JerryLead/spark,nlalevee/spark,yanboliang/spark,taroplus/spark,HyukjinKwon/spark,xflin/spark,andrewor14/spark,wzhfy/spark,akopich/spark,stanzhai/spark,ahnqirage/spark,mahak/spark,gengliangwang/spark,mahak/spark,WindCanDie/spark,wzhfy/spark,highfei2011/spark,apache-spark-on-k8s/spark,adrian-ionescu/apache-spark,WindCanDie/spark,zhouyejoe/spark,wzhfy/spark,wangmiao1981/spark,sahilTakiar/spark,debugger87/spark,1haodian/spark,zzcclp/spark,setjet/spark,highfei2011/spark,maropu/spark,srowen/spark,gioenn/xSpark,maropu/spark,apache-spark-on-k8s/spark,hhbyyh/spark,szhem/spark,eyalfa/spark,shuangshuangwang/spark,kiszk/spark,witgo/spark,SHASHANKB/spark,jkbradley/spark,tengpeng/spark,huang1900/spark,ConeyLiu/spark,andrewor14/spark,milliman/spark,nlalevee/spark,liutang123/spark,wangyum/spark,minixalpha/spark,ibm-research-ireland/sparkoscope,sureshthalamati/spark,WeichenXu123/spark,kissmetrics/spark,MLnick/spark,ajaysaini725/spark,sachintyagi22/spark,haowu80s/spark,narahari92/spark,michalsenkyr/spark,shaneknapp/spark,icexelloss/spark,MLnick/spark,andrewor14/iolap,brad-kaiser/spark,shaneknapp/spark,mzl9039/spark,nilsgrabbert/spark,maropu/spark,kevinyu98/spark,JoshRosen/spark,gengliangwang/spark,sureshthalamati/spark,matthewfranglen/spark,caneGuy/spark,jkbradley/spark,narahari92/spark,szhem/spark,xuanyuanking/spark,UndeadBaneGitHub/spark,yanboliang/spark,nchammas/spark,kiszk/spark,kiszk/spark,ddna1021/spark,apache/spark,wangyum/spark,BryanCutler/spark,poffuomo/spark,skonto/spark,ioana-delaney/spark,ptkool/spark,Panos-Bletsos/spark-cost-model-optimizer,ioana-delaney/spark,ptkool/spark,SHASHANKB/spark,publicRoman/spark,eyalfa/spark,apache/spark,jlopezmalla/spark,caneGuy/spark,joseph-torres/spark,JoshRosen/spark,cin/spark,techaddict/spark,highfei2011/spark,kissmetrics/spark,maropu/spark,zuotingbing/spark,ddna1021/spark,guoxiaolongzte/spark,milliman/spark,stanzhai/spark,nchammas/spark,ioana-delaney/spark,michalsenkyr/spark,tejasapatil/spark,adrian-ionescu/apache-spark,poffuomo/spark,map222/spark,cloud-fan/spark,dbtsai/spark,stanzhai/spark,holdenk/spark,sachintyagi22/spark,ueshin/apache-spark,map222/spark,tejasapatil/spark,holdenk/spark,kimoonkim/spark,gengliangwang/spark,nchammas/spark,hhbyyh/spark,eyalfa/spark,xuanyuanking/spark,UndeadBaneGitHub/spark,someorz/spark,poffuomo/spark,1haodian/spark,map222/spark,shuangshuangwang/spark,SnappyDataInc/spark,huang1900/spark,bdrillard/spark,dhruve/spark,bOOm-X/spark,mahak/spark,hvanhovell/spark,pronix/spark,tejasapatil/spark,guoxiaolongzte/spark,hhbyyh/spark,someorz/spark,szhem/spark,byakuinss/spark,mahak/spark,poffuomo/spark,zuotingbing/spark,facaiy/spark,WindCanDie/spark,publicRoman/spark,andrewor14/spark,ron8hu/spark,WeichenXu123/spark,nilsgrabbert/spark,techaddict/spark,WeichenXu123/spark,xflin/spark,JoshRosen/spark,shubhamchopra/spark,janewangfb/spark,lvdongr/spark,apache-spark-on-k8s/spark,skonto/spark,michalsenkyr/spark,rekhajoshm/spark,gengliangwang/spark,facaiy/spark,akopich/spark,mike0sv/spark,caneGuy/spark,alunarbeach/spark,mdespriee/spark,markhamstra/spark,nilsgrabbert/spark,rekhajoshm/spark,sureshthalamati/spark,sureshthalamati/spark,rezasafi/spark,kimoonkim/spark,vinodkc/spark,markhamstra/spark,maropu/spark,maropu/spark,liutang123/spark,kimoonkim/spark,kimoonkim/spark,jlopezmalla/spark,Panos-Bletsos/spark-cost-model-optimizer,kiszk/spark,gioenn/xSpark,haowu80s/spark,ibm-research-ireland/sparkoscope,aray/spark,akopich/spark,JerryLead/spark,SnappyDataInc/spark,janewangfb/spark,ddna1021/spark,nilsgrabbert/spark,vinodkc/spark,cin/spark,rikima/spark,cloud-fan/spark,jrshust/spark,rezasafi/spark,ddna1021/spark,shubhamchopra/spark,caneGuy/spark,highfei2011/spark,ibm-research-ireland/sparkoscope,1haodian/spark,ericvandenbergfb/spark,icexelloss/spark,goldmedal/spark,mdespriee/spark,caneGuy/spark,yanboliang/spark,jianran/spark,nlalevee/spark,bOOm-X/spark,jianran/spark,wzhfy/spark,BryanCutler/spark,andrewor14/iolap,map222/spark,rikima/spark,liutang123/spark,shaneknapp/spark,actuaryzhang/spark,huang1900/spark,tengpeng/spark,srowen/spark,kiszk/spark,patrick-nicholson/spark,lxsmnv/spark,gengliangwang/spark,guoxiaolongzte/spark,witgo/spark,ajaysaini725/spark,ajaysaini725/spark,ibm-research-ireland/sparkoscope,zzcclp/spark,witgo/spark,haowu80s/spark,jiangxb1987/spark,rezasafi/spark,ueshin/apache-spark,narahari92/spark,JerryLead/spark,mike0sv/spark,ioana-delaney/spark,esi-mineset/spark,andrewor14/iolap,dbtsai/spark,huang1900/spark,guoxiaolongzte/spark,dongjoon-hyun/spark,sachintyagi22/spark,UndeadBaneGitHub/spark,ericvandenbergfb/spark,1haodian/spark,pronix/spark,HyukjinKwon/spark,cloud-fan/spark,jiangxb1987/spark,debugger87/spark,vinodkc/spark,chuckchen/spark,byakuinss/spark,tengpeng/spark,big-pegasus/spark,chuckchen/spark,patrick-nicholson/spark,LantaoJin/spark,hhbyyh/spark,michalsenkyr/spark,ddna1021/spark,michalsenkyr/spark,setjet/spark,rikima/spark,rednaxelafx/apache-spark,skonto/spark,loneknightpy/spark,ConeyLiu/spark,shaneknapp/spark,minixalpha/spark,someorz/spark,ConeyLiu/spark,mzl9039/spark,aray/spark,lvdongr/spark,highfei2011/spark,hhbyyh/spark,rednaxelafx/apache-spark,mahak/spark,aray/spark,pgandhi999/spark,setjet/spark,kevinyu98/spark,someorz/spark,loneknightpy/spark,loneknightpy/spark,nchammas/spark,markhamstra/spark,gioenn/xSpark,andrewor14/spark,shaneknapp/spark,zzcclp/spark,narahari92/spark,liyichao/spark,MLnick/spark,nchammas/spark,brad-kaiser/spark,saturday-shi/spark,vinodkc/spark,bdrillard/spark,jrshust/spark,zero323/spark,narahari92/spark,ptkool/spark,1haodian/spark,dbtsai/spark,adrian-ionescu/apache-spark,debugger87/spark,xflin/spark,facaiy/spark,ptkool/spark,big-pegasus/spark,jiangxb1987/spark,kimoonkim/spark,BryanCutler/spark,aosagie/spark,gengliangwang/spark,facaiy/spark,chuckchen/spark,metamx/spark,cloud-fan/spark,setjet/spark,mdespriee/spark,someorz/spark,cin/spark,esi-mineset/spark,xuanyuanking/spark,kevinyu98/spark,JerryLead/spark,milliman/spark,cloud-fan/spark,JerryLead/spark,milliman/spark,zero323/spark,shuangshuangwang/spark,bOOm-X/spark,joseph-torres/spark,minixalpha/spark,wangmiao1981/spark,facaiy/spark,facaiy/spark,zhouyejoe/spark,byakuinss/spark,JerryLead/spark,srowen/spark,pronix/spark,ueshin/apache-spark,taroplus/spark,yanboliang/spark,zero323/spark,ibm-research-ireland/sparkoscope,bOOm-X/spark,ioana-delaney/spark,pgandhi999/spark,panfengfeng/spark,saturday-shi/spark,saltstar/spark,lvdongr/spark,chuckchen/spark,rezasafi/spark,holdenk/spark,bdrillard/spark,tengpeng/spark,esi-mineset/spark,mzl9039/spark,apache-spark-on-k8s/spark,bravo-zhang/spark,tejasapatil/spark,stanzhai/spark,zero323/spark,zzcclp/spark,UndeadBaneGitHub/spark,lvdongr/spark,saltstar/spark,mzl9039/spark,icexelloss/spark,rekhajoshm/spark,wangmiao1981/spark,xuanyuanking/spark,minixalpha/spark,SnappyDataInc/spark,srowen/spark,liyichao/spark,rezasafi/spark,janewangfb/spark,andrewor14/iolap,zuotingbing/spark,pgandhi999/spark,dbtsai/spark,huang1900/spark,huang1900/spark,JoshRosen/spark,hvanhovell/spark,witgo/spark,mahak/spark,pgandhi999/spark,kissmetrics/spark,wzhfy/spark,dongjoon-hyun/spark,hhbyyh/spark,taroplus/spark,ron8hu/spark,shuangshuangwang/spark,debugger87/spark,brad-kaiser/spark,markhamstra/spark,panfengfeng/spark,bdrillard/spark,witgo/spark,chuckchen/spark,ericvandenbergfb/spark,SnappyDataInc/spark,apache/spark,zhouyejoe/spark,LantaoJin/spark,hvanhovell/spark,joseph-torres/spark,lxsmnv/spark,bravo-zhang/spark,ron8hu/spark,skonto/spark,mzl9039/spark,nchammas/spark,stanzhai/spark,setjet/spark,dhruve/spark,shubhamchopra/spark,yanboliang/spark,zuotingbing/spark,jianran/spark,aokolnychyi/spark,BryanCutler/spark,rednaxelafx/apache-spark,witgo/spark,gengliangwang/spark,sachintyagi22/spark,kissmetrics/spark,saturday-shi/spark,lvdongr/spark,aray/spark,actuaryzhang/spark,ConeyLiu/spark,metamx/spark,liutang123/spark,spark-test/spark,shubhamchopra/spark,rikima/spark,yanboliang/spark,eyalfa/spark,darionyaphet/spark,ahnqirage/spark,esi-mineset/spark,jkbradley/spark,mdespriee/spark,xuanyuanking/spark,1haodian/spark,xflin/spark,LantaoJin/spark,ron8hu/spark,dhruve/spark,sahilTakiar/spark,zzcclp/spark,vinodkc/spark,jlopezmalla/spark,adrian-ionescu/apache-spark,kiszk/spark,mdespriee/spark,liyichao/spark,ConeyLiu/spark,apache/spark,stanzhai/spark,esi-mineset/spark,SHASHANKB/spark,darionyaphet/spark,big-pegasus/spark,dbtsai/spark,milliman/spark,holdenk/spark,kissmetrics/spark,saltstar/spark,zhouyejoe/spark,zero323/spark,akopich/spark,andrewor14/iolap,ptkool/spark,patrick-nicholson/spark,aosagie/spark,Aegeaner/spark,taroplus/spark,ahnqirage/spark,lxsmnv/spark,zhouyejoe/spark,lvdongr/spark,shuangshuangwang/spark,jianran/spark,saturday-shi/spark,xflin/spark,ConeyLiu/spark,publicRoman/spark,cin/spark,LantaoJin/spark,rikima/spark,rezasafi/spark,haowu80s/spark,goldmedal/spark,zhouyejoe/spark,SnappyDataInc/spark,HyukjinKwon/spark,szhem/spark,byakuinss/spark,LantaoJin/spark,jianran/spark,saturday-shi/spark,WindCanDie/spark,narahari92/spark,saltstar/spark,wzhfy/spark,aokolnychyi/spark,aosagie/spark,wangmiao1981/spark,bOOm-X/spark,dongjoon-hyun/spark,nlalevee/spark,liutang123/spark,MLnick/spark,alunarbeach/spark,aokolnychyi/spark,saturday-shi/spark,aokolnychyi/spark,aray/spark,esi-mineset/spark,ron8hu/spark,metamx/spark,techaddict/spark,mzl9039/spark,goldmedal/spark,narahari92/spark,mike0sv/spark,andrewor14/spark,huang1900/spark,bdrillard/spark,andrewor14/iolap,BryanCutler/spark,MLnick/spark,aokolnychyi/spark,pronix/spark,actuaryzhang/spark,gioenn/xSpark,markhamstra/spark,xuanyuanking/spark,zuotingbing/spark,ericvandenbergfb/spark,minixalpha/spark,lxsmnv/spark,rikima/spark,mdespriee/spark,mike0sv/spark,dongjoon-hyun/spark,rezasafi/spark,ueshin/apache-spark,adrian-ionescu/apache-spark,hvanhovell/spark,skonto/spark,alunarbeach/spark,aokolnychyi/spark,sureshthalamati/spark,aokolnychyi/spark,sachintyagi22/spark,WindCanDie/spark,highfei2011/spark,Aegeaner/spark,publicRoman/spark,jkbradley/spark,andrewor14/spark,saturday-shi/spark,spark-test/spark,sahilTakiar/spark,jrshust/spark,WindCanDie/spark,holdenk/spark,haowu80s/spark,tengpeng/spark,SnappyDataInc/spark,nilsgrabbert/spark,wzhfy/spark,liutang123/spark,pgandhi999/spark,WindCanDie/spark,techaddict/spark,goldmedal/spark,Aegeaner/spark,tengpeng/spark,rednaxelafx/apache-spark,taroplus/spark,ajaysaini725/spark,goldmedal/spark,cloud-fan/spark,rekhajoshm/spark,apache-spark-on-k8s/spark,BryanCutler/spark,HyukjinKwon/spark,lxsmnv/spark,taroplus/spark,bravo-zhang/spark,panfengfeng/spark,SHASHANKB/spark,big-pegasus/spark,hhbyyh/spark,bdrillard/spark,adrian-ionescu/apache-spark,Aegeaner/spark,mike0sv/spark,sahilTakiar/spark,jrshust/spark,JerryLead/spark,dhruve/spark,panfengfeng/spark,apache/spark,big-pegasus/spark,sachintyagi22/spark,apache/spark,eyalfa/spark,saltstar/spark,srowen/spark,jianran/spark,vinodkc/spark,shubhamchopra/spark,dbtsai/spark,shaneknapp/spark,holdenk/spark,lxsmnv/spark,milliman/spark,nlalevee/spark,janewangfb/spark,sahilTakiar/spark,patrick-nicholson/spark,metamx/spark,byakuinss/spark,JoshRosen/spark,milliman/spark,wangmiao1981/spark,kissmetrics/spark,panfengfeng/spark,techaddict/spark,setjet/spark,ioana-delaney/spark,dongjoon-hyun/spark,janewangfb/spark,ddna1021/spark,LantaoJin/spark,srowen/spark,tengpeng/spark,wangyum/spark,liyichao/spark,nchammas/spark,wangyum/spark,darionyaphet/spark,HyukjinKwon/spark,brad-kaiser/spark,bdrillard/spark,map222/spark,maropu/spark,wangyum/spark,jiangxb1987/spark,jkbradley/spark,bOOm-X/spark,nlalevee/spark,1haodian/spark,spark-test/spark,jiangxb1987/spark,poffuomo/spark,skonto/spark,debugger87/spark,kissmetrics/spark,ddna1021/spark,HyukjinKwon/spark,lvdongr/spark,debugger87/spark,dongjoon-hyun/spark,skonto/spark,BryanCutler/spark,actuaryzhang/spark,LantaoJin/spark,zzcclp/spark,esi-mineset/spark,jkbradley/spark,zuotingbing/spark,ibm-research-ireland/sparkoscope,byakuinss/spark,kevinyu98/spark,akopich/spark,ahnqirage/spark,l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