[SPARK-13300][DOCUMENTATION] Added pygments.rb dependancy
[SPARK-13300][DOCUMENTATION] Added pygments.rb dependancy

Looks like pygments.rb gem is also required for jekyll build to work. At least on Ubuntu/RHEL I could not do build without this dependency. So added this to steps.

Author: Amit Dev <amitdev@gmail.com>

Closes #11180 from amitdev/master.

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