pgsql: Add: > > * Reduce XID consumption of read-only queries > >

Log Message:
-----------
Add:

* Reduce XID consumption of read-only queries

http://archives.postgresql.org/pgsql-hackers/2007-08/msg00516.php

Modified Files:
--------------
pgsql/doc/src/FAQ:
TODO.html (r1.712 -> r1.713)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/FAQ/TODO.html?r1=1.712&r2=1.713)