cmake-mode.el: fix "docstring wider than 80 characters" warning

Fixes:
    In cmake-help:
    cmake-mode.el:492:2: Warning: docstring wider than 80 characters

Auxiliary/cmake-mode.el

@@ -480,7 +480,8 @@ and store the result as a list in LISTVAR."
 
 ;;;###autoload
 (defun cmake-help ()
-  "Queries for any of the four available help topics and prints out the appropriate page."
+  "Queries for any of the four available help topics and prints out the
+appropriate page."
   (interactive)
   (let* ((default-entry (cmake-symbol-at-point))
          (command-list (cmake-get-list "command"))