Disable special-keys option by default

It's probably too surprising to have enabled by default.

README.org

@@ -1,6 +1,8 @@
 * which-key 
 [[http://melpa.org/#/which-key][http://melpa.org/packages/which-key-badge.svg]] [[http://stable.melpa.org/#/which-key][file:http://stable.melpa.org/packages/which-key-badge.svg]]
-** What's New
+** Semi-Recent Changes
+- =which-key-special-keys= is now disabled by default. See the docstring for the
+  old setting.
 - =C-h= commands! Now =C-h= will prompt you will several options instead of
   going directly to the next page. You can (see =which-key-C-h-map=)
   - Cycle through the pages forward with =n= (or =C-n=)

which-key.el

@@ -150,9 +150,12 @@ the element is a cons cell, it should take the form (regexp .
 face to apply)."
   :group 'which-key)
 
-(defcustom which-key-special-keys '("SPC" "TAB" "RET" "ESC" "DEL")
+(defcustom which-key-special-keys '()
   "These keys will automatically be truncated to one character
-and have `which-key-special-key-face' applied to them."
+and have `which-key-special-key-face' applied to them. This is
+disabled by default. Try this to see the effect.
+
+\(setq which-key-special-keys '(\"SPC\" \"TAB\" \"RET\" \"ESC\" \"DEL\")\)"
   :group 'which-key
   :type '(repeat string))