Some more cleanup of CVS keyword noise.

Poking around for remaining occurrences of CVS keyword strings, I came
across one that apparently reflects the use of a $Revision: ...$ string
in the original input data.  Dunno why anybody would be using that in
an MTA's Received: lines, but there it is.  Put it back to the way that
it was originally, according to inspection of the CVS repo.

src/backend/optimizer/plan/README

@@ -10,7 +10,7 @@ From owner-pgsql-hackers@hub.org Fri Feb 13 09:01:19 1998
 Received: from renoir.op.net (root@renoir.op.net [209.152.193.4])
 	by candle.pha.pa.us (8.8.5/8.8.5) with ESMTP id JAA11576
 	for <maillist@candle.pha.pa.us>; Fri, 13 Feb 1998 09:01:17 -0500 (EST)
-Received: from hub.org (hub.org [209.47.148.200]) by renoir.op.net (o1/$Revision: 1.4 $) with ESMTP id IAA09761 for <maillist@candle.pha.pa.us>; Fri, 13 Feb 1998 08:41:22 -0500 (EST)
+Received: from hub.org (hub.org [209.47.148.200]) by renoir.op.net (o1/$Revision: 1.14 $) with ESMTP id IAA09761 for <maillist@candle.pha.pa.us>; Fri, 13 Feb 1998 08:41:22 -0500 (EST)
 Received: from localhost (majordom@localhost) by hub.org (8.8.8/8.7.5) with SMTP id IAA08135; Fri, 13 Feb 1998 08:40:17 -0500 (EST)
 Received: by hub.org (TLB v0.10a (1.23 tibbs 1997/01/09 00:29:32)); Fri, 13 Feb 1998 08:38:42 -0500 (EST)
 Received: (from majordom@localhost) by hub.org (8.8.8/8.7.5) id IAA06646 for pgsql-hackers-outgoing; Fri, 13 Feb 1998 08:38:35 -0500 (EST)