Update HISTORY.md
Update HISTORY.md

Summary: Updating HISTORY.md to reflect changes in PlainTable index

Test Plan: no need

Reviewers: sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D20229

zhangpng/rocksdb,wskplho/rocksdb,caijieming-baidu/rocksdb,rDSN-Projects/rocksdb.replicated,alihalabyah/rocksdb,fengshao0907/rocksdb,skunkwerks/rocksdb,fengshao0907/rocksdb,sorphi/rocksdb,tsheasha/rocksdb,vashstorm/rocksdb,zhangpng/rocksdb,JoeWoo/rocksdb,vashstorm/rocksdb,alihalabyah/rocksdb,facebook/rocksdb,ylong/rocksdb,JackLian/rocksdb,anagav/rocksdb,NickCis/rocksdb,anagav/rocksdb,ryneli/rocksdb,dkorolev/rocksdb,msb-at-yahoo/rocksdb,fengshao0907/rocksdb,SunguckLee/RocksDB,caijieming-baidu/rocksdb,bbiao/rocksdb,makelivedotnet/rocksdb,siddhartharay007/rocksdb,IMCG/RcoksDB,wenduo/rocksdb,tschottdorf/rocksdb,JohnPJenkins/rocksdb,amyvmiwei/rocksdb,amyvmiwei/rocksdb,alihalabyah/rocksdb,makelivedotnet/rocksdb,alihalabyah/rocksdb,temicai/rocksdb,wlqGit/rocksdb,Andymic/rocksdb,JackLian/rocksdb,kaschaeffer/rocksdb,kaschaeffer/rocksdb,facebook/rocksdb,flabby/rocksdb,biddyweb/rocksdb,siddhartharay007/rocksdb,sorphi/rocksdb,SunguckLee/RocksDB,ryneli/rocksdb,vmx/rocksdb,lgscofield/rocksdb,luckywhu/rocksdb,msb-at-yahoo/rocksdb,mbarbon/rocksdb,alihalabyah/rocksdb,skunkwerks/rocksdb,sorphi/rocksdb,temicai/rocksdb,ryneli/rocksdb,ylong/rocksdb,jalexanderqed/rocksdb,skunkwerks/rocksdb,OverlordQ/rocksdb,norton/rocksdb,ryneli/rocksdb,vashstorm/rocksdb,NickCis/rocksdb,wat-ze-hex/rocksdb,wat-ze-hex/rocksdb,OverlordQ/rocksdb,biddyweb/rocksdb,wenduo/rocksdb,lgscofield/rocksdb,Vaisman/rocksdb,tsheasha/rocksdb,vmx/rocksdb,mbarbon/rocksdb,zhangpng/rocksdb,virtdb/rocksdb,luckywhu/rocksdb,Vaisman/rocksdb,wskplho/rocksdb,SunguckLee/RocksDB,hobinyoon/rocksdb,wat-ze-hex/rocksdb,virtdb/rocksdb,temicai/rocksdb,rDSN-Projects/rocksdb.replicated,Andymic/rocksdb,ryneli/rocksdb,OverlordQ/rocksdb,vmx/rocksdb,Applied-Duality/rocksdb,lgscofield/rocksdb,rDSN-Projects/rocksdb.replicated,Applied-Duality/rocksdb,ryneli/rocksdb,JohnPJenkins/rocksdb,JohnPJenkins/rocksdb,lgscofield/rocksdb,siddhartharay007/rocksdb,Applied-Duality/rocksdb,siddhartharay007/rocksdb,zhangpng/rocksdb,geraldoandradee/rocksdb,biddyweb/rocksdb,kaschaeffer/rocksdb,tizzybec/rocksdb,ylong/rocksdb,sorphi/rocksdb,RyanTech/rocksdb,RyanTech/rocksdb,biddyweb/rocksdb,tsheasha/rocksdb,JohnPJenkins/rocksdb,NickCis/rocksdb,tschottdorf/rocksdb,wenduo/rocksdb,tsheasha/rocksdb,wlqGit/rocksdb,dkorolev/rocksdb,virtdb/rocksdb,jalexanderqed/rocksdb,msb-at-yahoo/rocksdb,flabby/rocksdb,mbarbon/rocksdb,SunguckLee/RocksDB,skunkwerks/rocksdb,OverlordQ/rocksdb,JackLian/rocksdb,kaschaeffer/rocksdb,hobinyoon/rocksdb,tschottdorf/rocksdb,virtdb/rocksdb,dkorolev/rocksdb,JoeWoo/rocksdb,geraldoandradee/rocksdb,vmx/rocksdb,wskplho/rocksdb,SunguckLee/RocksDB,JohnPJenkins/rocksdb,caijieming-baidu/rocksdb,mbarbon/rocksdb,fengshao0907/rocksdb,JohnPJenkins/rocksdb,facebook/rocksdb,lgscofield/rocksdb,flabby/rocksdb,rDSN-Projects/rocksdb.replicated,wenduo/rocksdb,luckywhu/rocksdb,rDSN-Projects/rocksdb.replicated,amyvmiwei/rocksdb,dkorolev/rocksdb,amyvmiwei/rocksdb,SunguckLee/RocksDB,vashstorm/rocksdb,hobinyoon/rocksdb,amyvmiwei/rocksdb,wenduo/rocksdb,caijieming-baidu/rocksdb,Andymic/rocksdb,kaschaeffer/rocksdb,RyanTech/rocksdb,bbiao/rocksdb,OverlordQ/rocksdb,bbiao/rocksdb,caijieming-baidu/rocksdb,bbiao/rocksdb,wenduo/rocksdb,sorphi/rocksdb,JoeWoo/rocksdb,anagav/rocksdb,tsheasha/rocksdb,biddyweb/rocksdb,jalexanderqed/rocksdb,wskplho/rocksdb,skunkwerks/rocksdb,temicai/rocksdb,facebook/rocksdb,Applied-Duality/rocksdb,JackLian/rocksdb,wlqGit/rocksdb,JoeWoo/rocksdb,bbiao/rocksdb,skunkwerks/rocksdb,wenduo/rocksdb,facebook/rocksdb,Andymic/rocksdb,geraldoandradee/rocksdb,tizzybec/rocksdb,RyanTech/rocksdb,jalexanderqed/rocksdb,jalexanderqed/rocksdb,tsheasha/rocksdb,hobinyoon/rocksdb,wlqGit/rocksdb,amyvmiwei/rocksdb,biddyweb/rocksdb,fengshao0907/rocksdb,temicai/rocksdb,OverlordQ/rocksdb,Vaisman/rocksdb,zhangpng/rocksdb,anagav/rocksdb,tizzybec/rocksdb,JackLian/rocksdb,vashstorm/rocksdb,ylong/rocksdb,vmx/rocksdb,msb-at-yahoo/rocksdb,SunguckLee/RocksDB,norton/rocksdb,OverlordQ/rocksdb,makelivedotnet/rocksdb,siddhartharay007/rocksdb,wat-ze-hex/rocksdb,vmx/rocksdb,wat-ze-hex/rocksdb,hobinyoon/rocksdb,tizzybec/rocksdb,dkorolev/rocksdb,norton/rocksdb,JoeWoo/rocksdb,norton/rocksdb,sorphi/rocksdb,vmx/rocksdb,caijieming-baidu/rocksdb,JackLian/rocksdb,ylong/rocksdb,tsheasha/rocksdb,rDSN-Projects/rocksdb.replicated,anagav/rocksdb,norton/rocksdb,wat-ze-hex/rocksdb,dkorolev/rocksdb,anagav/rocksdb,Andymic/rocksdb,tsheasha/rocksdb,skunkwerks/rocksdb,IMCG/RcoksDB,hobinyoon/rocksdb,wskplho/rocksdb,tizzybec/rocksdb,wenduo/rocksdb,alihalabyah/rocksdb,Applied-Duality/rocksdb,wskplho/rocksdb,siddhartharay007/rocksdb,Andymic/rocksdb,biddyweb/rocksdb,luckywhu/rocksdb,virtdb/rocksdb,IMCG/RcoksDB,luckywhu/rocksdb,makelivedotnet/rocksdb,makelivedotnet/rocksdb,IMCG/RcoksDB,IMCG/RcoksDB,geraldoandradee/rocksdb,bbiao/rocksdb,zhangpng/rocksdb,Andymic/rocksdb,tschottdorf/rocksdb,amyvmiwei/rocksdb,NickCis/rocksdb,virtdb/rocksdb,Andymic/rocksdb,bbiao/rocksdb,NickCis/rocksdb,caijieming-baidu/rocksdb,dkorolev/rocksdb,wskplho/rocksdb,facebook/rocksdb,IMCG/RcoksDB,geraldoandradee/rocksdb,mbarbon/rocksdb,norton/rocksdb,RyanTech/rocksdb,Vaisman/rocksdb,Vaisman/rocksdb,lgscofield/rocksdb,Applied-Duality/rocksdb,siddhartharay007/rocksdb,geraldoandradee/rocksdb,msb-at-yahoo/rocksdb,temicai/rocksdb,tschottdorf/rocksdb,vmx/rocksdb,wlqGit/rocksdb,norton/rocksdb,mbarbon/rocksdb,fengshao0907/rocksdb,wat-ze-hex/rocksdb,ylong/rocksdb,luckywhu/rocksdb,hobinyoon/rocksdb,ryneli/rocksdb,wat-ze-hex/rocksdb,virtdb/rocksdb,RyanTech/rocksdb,tizzybec/rocksdb,JackLian/rocksdb,lgscofield/rocksdb,kaschaeffer/rocksdb,alihalabyah/rocksdb,wlqGit/rocksdb,anagav/rocksdb,facebook/rocksdb,SunguckLee/RocksDB,geraldoandradee/rocksdb,RyanTech/rocksdb,JohnPJenkins/rocksdb,norton/rocksdb,wlqGit/rocksdb,facebook/rocksdb,flabby/rocksdb,msb-at-yahoo/rocksdb,bbiao/rocksdb,IMCG/RcoksDB,NickCis/rocksdb,jalexanderqed/rocksdb,hobinyoon/rocksdb,fengshao0907/rocksdb,zhangpng/rocksdb,Vaisman/rocksdb,Vaisman/rocksdb,temicai/rocksdb,jalexanderqed/rocksdb,vashstorm/rocksdb,flabby/rocksdb,kaschaeffer/rocksdb,tizzybec/rocksdb,JoeWoo/rocksdb,ylong/rocksdb,luckywhu/rocksdb,NickCis/rocksdb,JoeWoo/rocksdb,rDSN-Projects/rocksdb.replicated,makelivedotnet/rocksdb,Applied-Duality/rocksdb,vashstorm/rocksdb,flabby/rocksdb,makelivedotnet/rocksdb,sorphi/rocksdb,mbarbon/rocksdb,tschottdorf/rocksdb,flabby/rocksdb