Doc update from Roberto Mello: improved versions of instr() examples.
Doc update from Roberto Mello: improved versions of instr() examples.

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