Log Message:
-----------
Correct overstatement in locking docs: we said ExclusiveLock is never
taken automatically, but this is only true with respect to user tables.
Modified Files:
--------------
pgsql/doc/src/sgml:
mvcc.sgml (r2.46 -> r2.47)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/mvcc.sgml.diff?r1=2.46&r2=2.47)