[DOC][MINOR] Kafka doc: breakup into lines
[DOC][MINOR] Kafka doc: breakup into lines

## Before

![before](https://cloud.githubusercontent.com/assets/15843379/20340231/99b039fe-ac1b-11e6-9ba9-b44582427459.png)

## After

![after](https://cloud.githubusercontent.com/assets/15843379/20340236/9d5796e2-ac1b-11e6-92bb-6da40ba1a383.png)

Author: Liwei Lin <lwlin7@gmail.com>

Closes #15903 from lw-lin/kafka-doc-lines.

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