Log Message:-----------Fix HISTORY.html build using </link>, not </>.
Modified Files:-------------- pgsql/doc/src/sgml: release-9.0.sgml (r2.20 -> r2.21) (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/release-9.0.sgml?r1=2.20&r2=2.21)
