Fix wording of section comparing triggers and rules;  old wording as confusing.
Fix wording of section comparing triggers and rules;  old wording as
confusing.

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