Fix typo in screen.texi.

doc/emacs/ChangeLog

+2012-10-27  Bastien Guerry  <bzg@gnu.org>
+
+	* screen.texi (Menu Bar): Fix typo.
+
 2012-10-27  Chong Yidong  <cyd@gnu.org>
 
 	* frames.texi (Mouse Avoidance): Mention new variable

doc/emacs/screen.texi

@@ -314,5 +314,5 @@ the echo area.  You can use the up and down arrow keys to move through
 the menu to different items, and then you can type @key{RET} to select
 the item.  Each menu item is also designated by a letter or digit
 (usually the initial of some word in the item's name).  This letter or
-digit is separated from the item name by @samp{=>}.  You can type the
+digit is separated from the item name by @samp{==>}.  You can type the
 item's letter or digit to select the item.