Lots of doc corrections.

contrib/dblink/dblink.c

contrib/fuzzystrmatch/fuzzystrmatch.c

contrib/fuzzystrmatch/levenshtein.c

contrib/hstore/hstore_io.c

contrib/pg_upgrade/info.c

contrib/pg_upgrade/pg_upgrade.c

contrib/pg_upgrade/version_old_8_3.c

contrib/pgcrypto/crypt-des.c

contrib/pgcrypto/imath.c

contrib/pgcrypto/pgp-pgsql.c

contrib/sepgsql/label.c

contrib/sslinfo/sslinfo.c

doc/src/sgml/release-7.4.sgml

doc/src/sgml/release-8.0.sgml

doc/src/sgml/release-8.1.sgml

doc/src/sgml/release-8.2.sgml

src/Makefile.global.in

src/backend/access/gin/ginentrypage.c

src/backend/access/gin/ginfast.c

src/backend/access/heap/heapam.c