doc: Remove unnecessary RETURN statements from example.

Paul Jungwirth, reviewed by Ashutosh Bapat.

Discussion: http://postgr.es/m/e24a6a6d-5670-739b-00f3-41a226a80f25@illuminatedcomputing.com

doc/src/sgml/plpgsql.sgml

@@ -3999,13 +3999,10 @@ CREATE OR REPLACE FUNCTION process_emp_audit() RETURNS TRIGGER AS $emp_audit$
         --
         IF (TG_OP = 'DELETE') THEN
             INSERT INTO emp_audit SELECT 'D', now(), user, OLD.*;
-            RETURN OLD;
         ELSIF (TG_OP = 'UPDATE') THEN
             INSERT INTO emp_audit SELECT 'U', now(), user, NEW.*;
-            RETURN NEW;
         ELSIF (TG_OP = 'INSERT') THEN
             INSERT INTO emp_audit SELECT 'I', now(), user, NEW.*;
-            RETURN NEW;
         END IF;
         RETURN NULL; -- result is ignored since this is an AFTER trigger
     END;