custom-buffer-style doc fix

* lisp/cus-edit.el (custom-buffer-style): Document the `tree'
value (bug#20724).

diff --git a/lisp/cus-edit.el b/lisp/cus-edit.el
index ee0f14fe90e0afe2bb142bfb949ab2c61773ccf2..a1eb1d200164759febc4c2f993f6854db18f82e5 100644 (file)
--- a/lisp/cus-edit.el
+++ b/lisp/cus-edit.el
@@ -1499,11 +1499,12 @@ Return non-nil if user chooses to customize, for use in
 (defcustom custom-buffer-style 'links
   "Control the presentation style for customization buffers.
 The value should be a symbol, one of:
-
-brackets: groups nest within each other with big horizontal brackets.
-links: groups have links to subgroups."
+`brackets': groups nest within each other with big horizontal brackets.
+`links': groups have links to subgroups.
+`tree': display groups as trees."
   :type '(radio (const brackets)
-               (const links))
+               (const links)
+                (const tree))
   :group 'custom-buffer)
 
 (defcustom custom-buffer-done-kill nil