Update pg_hba.conf.sample with better examples and descriptions
Update pg_hba.conf.sample with better examples and descriptions

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