Update release history for releases 7.4.6, 7.3.8, 7.2.6.
Update release history for releases 7.4.6, 7.3.8, 7.2.6.

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