Update mention of diff.

contrib/mysql/README

@@ -4,6 +4,8 @@ The most recent version of my2pg.pl can be obtained from:
 
 	http://www.omnistarinc.com/~fonin/downloads.php#my2pg
 
+my2pg.diff has additional changes for CREATE FUNCTION.
+
 Another tool, mysql2pgsql, can be found at:
 
 	http://www.rot13.org/~dpavlin/sql.html