Improve documentation about array I/O representation.
Improve documentation about array I/O representation.

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