Thread: pgsql: Fix mistaken duplicate reference to max_fsm_pages, per bug #3926.

Log Message:
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Fix mistaken duplicate reference to max_fsm_pages, per bug #3926.
Also make links clickable.

Modified Files:
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    pgsql/doc/src/sgml/ref:
        vacuum.sgml (r1.50 -> r1.51)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/vacuum.sgml?r1=1.50&r2=1.51)