Update recovery_min_apply_delay docs for remote_apply mode.
Update recovery_min_apply_delay docs for remote_apply mode.

Bernd Helmle, reviewed by Thomas Munro, tweaked by me.

50wu/gpdb,adam8157/gpdb,xinzweb/gpdb,xinzweb/gpdb,greenplum-db/gpdb,lisakowen/gpdb,adam8157/gpdb,lisakowen/gpdb,xinzweb/gpdb,lisakowen/gpdb,adam8157/gpdb,xinzweb/gpdb,50wu/gpdb,50wu/gpdb,greenplum-db/gpdb,50wu/gpdb,adam8157/gpdb,50wu/gpdb,greenplum-db/gpdb,50wu/gpdb,lisakowen/gpdb,greenplum-db/gpdb,adam8157/gpdb,adam8157/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,lisakowen/gpdb,xinzweb/gpdb,xinzweb/gpdb,greenplum-db/gpdb,adam8157/gpdb,lisakowen/gpdb,50wu/gpdb,xinzweb/gpdb,greenplum-db/gpdb,xinzweb/gpdb,lisakowen/gpdb,adam8157/gpdb,lisakowen/gpdb,50wu/gpdb