Suggested patch to plpgsql docs (7.4beta)

Addition of one paragraph to the end of section 39.7.3.4 "FOR (integer
variant)"

Note that this is basically a WHILE loop, so if the lower bound is larger than
the upper bound the loop never executes it's contents:
  FOR i IN 10..1 LOOP
    RAISE NOTICE ''I do not raise a notice %'',i;
  END LOOP;

I wasn't sure and had to check, so I assume others might find this useful too.
--
  Richard Huxton
  Archonet Ltd