Update help which referred to Carbon version

In particular, state that MacVim does not source $VIMRUNTIME/macmap.vim.

runtime/doc/os_mac.txt

@@ -1,4 +1,4 @@
-*os_mac.txt*    For Vim version 7.1.  Last change: 2006 Apr 30
+*os_mac.txt*    For Vim version 7.1.  Last change: 2008 May 19
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar et al.
@@ -6,9 +6,13 @@
 
 					*mac* *Mac* *macintosh* *Macintosh*
 
-This file documents the particularities of the Macintosh version of Vim.
+This file documents the particularities of the Mac version of Vim.  It was
+written with the older Carbon version of Vim in mind.  If you are using the
+newer MacVim.app then please go to |macvim|.  Some of the information here
+does not apply to MacVim.app.
 
-NOTE: This file is a bit outdated.  You might find more useful info here:
+NOTE: This file is a bit outdated.  You might find more useful info on the old
+Carbon version of Vim here:
 	http://macvim.org/
 
 1. Filename Convention		|mac-filename|

runtime/doc/starting.txt

@@ -766,7 +766,8 @@ accordingly.  Vim proceeds in this order:
 	Note that this file is ALWAYS read in 'compatible' mode, since the
 	automatic resetting of 'compatible' is only done later.  Add a ":set
 	nocp" command if you like.
-	For the Macintosh the $VIMRUNTIME/macmap.vim is read.
+	For the Macintosh the $VIMRUNTIME/macmap.vim is read (not on
+	MacVim.app, this only applies to the older Carbon version).
 
 			  *VIMINIT* *.vimrc* *_vimrc* *EXINIT* *.exrc* *_exrc*
      c. Four places are searched for initializations.  The first that exists

runtime/doc/version7.txt

@@ -1177,6 +1177,8 @@ goes from 2.2 to 2.3. (Gordon Prieur)
 
 Mac: When starting up Vim will load the $VIMRUNTIME/macmap.vim script to
 define default command-key mappings. (mostly by Benji Fisher)
+This only applies to the older Carbon version of Vim, MacVim.app does not
+source this file.
 
 Mac: Add the selection type to the clipboard, so that Block, line and
 character selections can be used between two Vims. (Eckehard Berns)