Add Bob Devine's name to the optimizer README.

src/backend/optimizer/README

@@ -498,4 +498,9 @@ pathkey lists when computing the sort ordering needed for a mergejoin.  By
 eliminating the redundancy, we save time and improve planning, since the
 planner will more easily recognize equivalent orderings as being equivalent.
 
+Though Bob Devine <bob.devine@worldnet.att.net> was not involved in the 
+coding of our optimizer, he is available to field questions about
+optimizer topics.
+
 -- bjm & tgl
+