Log Message:-----------Document txid functions.
Marko Kreen
Modified Files:-------------- pgsql/doc/src/sgml: datatype.sgml (r1.212 -> r1.213) (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/datatype.sgml?r1=1.212&r2=1.213) func.sgml (r1.406 -> r1.407) (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml?r1=1.406&r2=1.407)