Update sgml for 6.4.* release changes.
Update sgml for 6.4.* release changes.

zeroae/postgres-xl,randomtask1155/gpdb,yuanzhao/gpdb,edespino/gpdb,foyzur/gpdb,jmcatamney/gpdb,cjcjameson/gpdb,foyzur/gpdb,yuanzhao/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,cjcjameson/gpdb,cjcjameson/gpdb,royc1/gpdb,tpostgres-projects/tPostgres,yuanzhao/gpdb,snaga/postgres-xl,50wu/gpdb,ahachete/gpdb,Quikling/gpdb,yuanzhao/gpdb,lisakowen/gpdb,yazun/postgres-xl,Chibin/gpdb,kaknikhil/gpdb,greenplum-db/gpdb,tpostgres-projects/tPostgres,zaksoup/gpdb,Chibin/gpdb,tangp3/gpdb,lintzc/gpdb,CraigHarris/gpdb,xuegang/gpdb,Chibin/gpdb,janebeckman/gpdb,chrishajas/gpdb,rubikloud/gpdb,postmind-net/postgres-xl,arcivanov/postgres-xl,lpetrov-pivotal/gpdb,snaga/postgres-xl,yuanzhao/gpdb,lintzc/gpdb,edespino/gpdb,foyzur/gpdb,chrishajas/gpdb,janebeckman/gpdb,lpetrov-pivotal/gpdb,jmcatamney/gpdb,ovr/postgres-xl,ahachete/gpdb,CraigHarris/gpdb,CraigHarris/gpdb,0x0FFF/gpdb,edespino/gpdb,ashwinstar/gpdb,xinzweb/gpdb,xuegang/gpdb,kmjungersen/PostgresXL,cjcjameson/gpdb,lisakowen/gpdb,chrishajas/gpdb,lisakowen/gpdb,zaksoup/gpdb,zaksoup/gpdb,tangp3/gpdb,adam8157/gpdb,edespino/gpdb,techdragon/Postgres-XL,ashwinstar/gpdb,Quikling/gpdb,lintzc/gpdb,kaknikhil/gpdb,0x0FFF/gpdb,ovr/postgres-xl,0x0FFF/gpdb,foyzur/gpdb,edespino/gpdb,techdragon/Postgres-XL,janebeckman/gpdb,pavanvd/postgres-xl,royc1/gpdb,adam8157/gpdb,postmind-net/postgres-xl,lintzc/gpdb,Postgres-XL/Postgres-XL,pavanvd/postgres-xl,tangp3/gpdb,greenplum-db/gpdb,postmind-net/postgres-xl,yazun/postgres-xl,randomtask1155/gpdb,lpetrov-pivotal/gpdb,jmcatamney/gpdb,xuegang/gpdb,Quikling/gpdb,atris/gpdb,adam8157/gpdb,snaga/postgres-xl,adam8157/gpdb,tpostgres-projects/tPostgres,kaknikhil/gpdb,zaksoup/gpdb,lisakowen/gpdb,lintzc/gpdb,Quikling/gpdb,arcivanov/postgres-xl,Chibin/gpdb,zeroae/postgres-xl,xinzweb/gpdb,jmcatamney/gpdb,50wu/gpdb,ahachete/gpdb,Postgres-XL/Postgres-XL,kmjungersen/PostgresXL,zeroae/postgres-xl,yazun/postgres-xl,edespino/gpdb,rvs/gpdb,50wu/gpdb,CraigHarris/gpdb,xinzweb/gpdb,edespino/gpdb,atris/gpdb,rvs/gpdb,randomtask1155/gpdb,oberstet/postgres-xl,kaknikhil/gpdb,postmind-net/postgres-xl,royc1/gpdb,ahachete/gpdb,greenplum-db/gpdb,rvs/gpdb,CraigHarris/gpdb,greenplum-db/gpdb,rvs/gpdb,tangp3/gpdb,foyzur/gpdb,chrishajas/gpdb,atris/gpdb,lintzc/gpdb,xuegang/gpdb,rubikloud/gpdb,techdragon/Postgres-XL,ashwinstar/gpdb,arcivanov/postgres-xl,zaksoup/gpdb,rvs/gpdb,lpetrov-pivotal/gpdb,50wu/gpdb,50wu/gpdb,Quikling/gpdb,yuanzhao/gpdb,foyzur/gpdb,randomtask1155/gpdb,Chibin/gpdb,yuanzhao/gpdb,greenplum-db/gpdb,janebeckman/gpdb,greenplum-db/gpdb,kaknikhil/gpdb,xuegang/gpdb,Chibin/gpdb,jmcatamney/gpdb,lisakowen/gpdb,zeroae/postgres-xl,royc1/gpdb,lintzc/gpdb,kmjungersen/PostgresXL,CraigHarris/gpdb,ashwinstar/gpdb,Quikling/gpdb,Chibin/gpdb,zaksoup/gpdb,chrishajas/gpdb,janebeckman/gpdb,ahachete/gpdb,pavanvd/postgres-xl,randomtask1155/gpdb,kaknikhil/gpdb,zaksoup/gpdb,lpetrov-pivotal/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,Chibin/gpdb,kmjungersen/PostgresXL,0x0FFF/gpdb,janebeckman/gpdb,yuanzhao/gpdb,ahachete/gpdb,edespino/gpdb,oberstet/postgres-xl,tangp3/gpdb,kaknikhil/gpdb,Chibin/gpdb,50wu/gpdb,0x0FFF/gpdb,janebeckman/gpdb,tangp3/gpdb,postmind-net/postgres-xl,xinzweb/gpdb,adam8157/gpdb,rvs/gpdb,lisakowen/gpdb,ovr/postgres-xl,kmjungersen/PostgresXL,yazun/postgres-xl,xinzweb/gpdb,techdragon/Postgres-XL,xuegang/gpdb,yuanzhao/gpdb,rubikloud/gpdb,atris/gpdb,lisakowen/gpdb,cjcjameson/gpdb,ahachete/gpdb,xuegang/gpdb,tangp3/gpdb,tpostgres-projects/tPostgres,royc1/gpdb,edespino/gpdb,rubikloud/gpdb,atris/gpdb,chrishajas/gpdb,lpetrov-pivotal/gpdb,janebeckman/gpdb,CraigHarris/gpdb,chrishajas/gpdb,royc1/gpdb,pavanvd/postgres-xl,lintzc/gpdb,0x0FFF/gpdb,ashwinstar/gpdb,kaknikhil/gpdb,rubikloud/gpdb,arcivanov/postgres-xl,foyzur/gpdb,0x0FFF/gpdb,randomtask1155/gpdb,techdragon/Postgres-XL,foyzur/gpdb,xinzweb/gpdb,rvs/gpdb,ahachete/gpdb,ovr/postgres-xl,janebeckman/gpdb,randomtask1155/gpdb,oberstet/postgres-xl,Quikling/gpdb,royc1/gpdb,tpostgres-projects/tPostgres,lintzc/gpdb,lisakowen/gpdb,randomtask1155/gpdb,Postgres-XL/Postgres-XL,rubikloud/gpdb,Quikling/gpdb,atris/gpdb,yazun/postgres-xl,cjcjameson/gpdb,zeroae/postgres-xl,lpetrov-pivotal/gpdb,rubikloud/gpdb,snaga/postgres-xl,kaknikhil/gpdb,cjcjameson/gpdb,oberstet/postgres-xl,xinzweb/gpdb,rvs/gpdb,arcivanov/postgres-xl,adam8157/gpdb,janebeckman/gpdb,ashwinstar/gpdb,rvs/gpdb,50wu/gpdb,arcivanov/postgres-xl,adam8157/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,cjcjameson/gpdb,yuanzhao/gpdb,rvs/gpdb,chrishajas/gpdb,snaga/postgres-xl,pavanvd/postgres-xl,ashwinstar/gpdb,zaksoup/gpdb,xuegang/gpdb,royc1/gpdb,CraigHarris/gpdb,adam8157/gpdb,CraigHarris/gpdb,atris/gpdb,rubikloud/gpdb,xuegang/gpdb,edespino/gpdb,Postgres-XL/Postgres-XL,Quikling/gpdb,Quikling/gpdb,atris/gpdb,oberstet/postgres-xl,0x0FFF/gpdb,ovr/postgres-xl,lpetrov-pivotal/gpdb,cjcjameson/gpdb,50wu/gpdb,Postgres-XL/Postgres-XL,kaknikhil/gpdb,Chibin/gpdb,cjcjameson/gpdb,tangp3/gpdb,xinzweb/gpdb