Open files with .cl extension in lisp-mode

I'm surprised that this isn't already the case.

Although most people use the .lisp extension, some do use .cl

modules/prelude-common-lisp.el

@@ -37,6 +37,9 @@
 ;; the SBCL configuration file is in Common Lisp
 (add-to-list 'auto-mode-alist '("\\.sbclrc$" . lisp-mode))
 
+;; Open files with .cl extension in lisp-mode
+(add-to-list 'auto-mode-alist '("\\.cl\\'" . lisp-mode))
+
 ;; Common Lisp support depends on SLIME being installed with Quicklisp
 (if (file-exists-p (expand-file-name "~/quicklisp/slime-helper.el"))
     (load (expand-file-name "~/quicklisp/slime-helper.el"))