Log Message:
-----------
Fix markup that doesn't work in HISTORY generation.
Modified Files:
--------------
pgsql/doc/src/sgml:
release.sgml (r1.539 -> r1.540)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/release.sgml?r1=1.539&r2=1.540)