Add file-fdw documentation example.
Add file-fdw documentation example.

Josh Berkus

kmjungersen/PostgresXL,adam8157/gpdb,techdragon/Postgres-XL,ashwinstar/gpdb,techdragon/Postgres-XL,adam8157/gpdb,zeroae/postgres-xl,pavanvd/postgres-xl,xinzweb/gpdb,ovr/postgres-xl,ovr/postgres-xl,50wu/gpdb,adam8157/gpdb,greenplum-db/gpdb,50wu/gpdb,postmind-net/postgres-xl,ashwinstar/gpdb,xinzweb/gpdb,yazun/postgres-xl,xinzweb/gpdb,50wu/gpdb,adam8157/gpdb,postmind-net/postgres-xl,ashwinstar/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,oberstet/postgres-xl,techdragon/Postgres-XL,Postgres-XL/Postgres-XL,yazun/postgres-xl,xinzweb/gpdb,greenplum-db/gpdb,adam8157/gpdb,arcivanov/postgres-xl,yazun/postgres-xl,lisakowen/gpdb,zeroae/postgres-xl,lisakowen/gpdb,greenplum-db/gpdb,snaga/postgres-xl,kmjungersen/PostgresXL,adam8157/gpdb,Postgres-XL/Postgres-XL,oberstet/postgres-xl,tpostgres-projects/tPostgres,postmind-net/postgres-xl,ashwinstar/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,50wu/gpdb,adam8157/gpdb,50wu/gpdb,arcivanov/postgres-xl,tpostgres-projects/tPostgres,xinzweb/gpdb,jmcatamney/gpdb,techdragon/Postgres-XL,xinzweb/gpdb,greenplum-db/gpdb,tpostgres-projects/tPostgres,pavanvd/postgres-xl,ovr/postgres-xl,50wu/gpdb,kmjungersen/PostgresXL,50wu/gpdb,ashwinstar/gpdb,arcivanov/postgres-xl,arcivanov/postgres-xl,snaga/postgres-xl,pavanvd/postgres-xl,jmcatamney/gpdb,50wu/gpdb,zeroae/postgres-xl,pavanvd/postgres-xl,Postgres-XL/Postgres-XL,lisakowen/gpdb,Postgres-XL/Postgres-XL,zeroae/postgres-xl,lisakowen/gpdb,arcivanov/postgres-xl,kmjungersen/PostgresXL,jmcatamney/gpdb,xinzweb/gpdb,snaga/postgres-xl,postmind-net/postgres-xl,arcivanov/postgres-xl,tpostgres-projects/tPostgres,kmjungersen/PostgresXL,zeroae/postgres-xl,lisakowen/gpdb,oberstet/postgres-xl,jmcatamney/gpdb,adam8157/gpdb,postmind-net/postgres-xl,ovr/postgres-xl,pavanvd/postgres-xl,greenplum-db/gpdb,lisakowen/gpdb,ashwinstar/gpdb,snaga/postgres-xl,jmcatamney/gpdb,ashwinstar/gpdb,tpostgres-projects/tPostgres,yazun/postgres-xl,jmcatamney/gpdb,techdragon/Postgres-XL,jmcatamney/gpdb,oberstet/postgres-xl,lisakowen/gpdb,oberstet/postgres-xl,ovr/postgres-xl,snaga/postgres-xl,lisakowen/gpdb,greenplum-db/gpdb,yazun/postgres-xl,Postgres-XL/Postgres-XL,xinzweb/gpdb