Log Message:
-----------
Minor cleanup of documentation for recently-added HISTFILE psql variable.
Modified Files:
--------------
pgsql/doc/src/sgml/ref:
psql-ref.sgml (r1.140 -> r1.141)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/psql-ref.sgml.diff?r1=1.140&r2=1.141)