pgsql: Add docs about postgres_fdw's setting of search_path and other G

Add docs about postgres_fdw's setting of search_path and other GUCs.

This behavior wasn't documented, but it should be because it's user-visible
in triggers and other functions executed on the remote server.
Per question from Adam Fuchs.

Back-patch to 9.3 where postgres_fdw was added.

Branch
------
REL9_3_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/5f1ee4777e13477a00ec65f8479b700ee8b64644

Modified Files
--------------
doc/src/sgml/postgres-fdw.sgml | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)

--
Sent via pgsql-committers mailing list (pgsql-committers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-committers