pgsql: Document ath vacuumdb --analyze does analyze _also_, not in place

Log Message:
-----------
Document ath vacuumdb --analyze does analyze _also_, not in place of
vacuum.

Modified Files:
--------------
pgsql/doc/src/sgml/ref:
vacuumdb.sgml (r1.44 -> r1.45)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/vacuumdb.sgml?r1=1.44&r2=1.45)