(battery-status-function): Fix doc, :type.

diff --git a/lisp/battery.el b/lisp/battery.el
index ccafa8bf21308fa29b96e52269349045ae4663e8..67e129b93309e647321ac88d56413a6e6b60e4bc 100644 (file)
--- a/lisp/battery.el
+++ b/lisp/battery.el
@@ -44,14 +44,14 @@
              (file-readable-p "/proc/apm"))
         'battery-linux-proc-apm))
   "*Function for getting battery status information.
-The function have to return an alist of conversion definitions.
-Cons cells are of the form
+The function has to return an alist of conversion definitions.
+Its cons cells are of the form
 
     (CONVERSION . REPLACEMENT-TEXT)
 
 CONVERSION is the character code of a \"conversion specification\"
 introduced by a `%' character in a control string."
-  :type 'function
+  :type '(choice (const nil) function)
   :group 'battery)
 
 (defcustom battery-echo-area-format