custom-buffer-style doc fix

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

(cherry picked from commit bcf0291d0cd02095b0809b1eb91f1e5c5c2ac5e3)

diff --git a/lisp/cus-edit.el b/lisp/cus-edit.el
index 9609a034c9711f590bda7de04eb85a8be8f26c3f..d7db3530099a8f6a4840f1475c795d054a38580e 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