avoid redundant banner in minified docs CSS

Gruntfile.js

@@ -196,7 +196,6 @@ module.exports = function (grunt) {
     cssmin: {
       compress: {
         options: {
-          banner: '<%= bannerDocs %>',
           keepSpecialComments: '*',
           noAdvanced: true, // turn advanced optimizations off until it's fixed in clean-css
           report: 'min',

docs/assets/css/docs.css

 /*csslint ids: false, overqualified-elements: false*/
 /*!
+ * Bootstrap Docs (http://getbootstrap.com)
  * Copyright 2011-2014 Twitter, Inc.
- *
  * Licensed under the Creative Commons Attribution 3.0 Unported License. For
  * details, see http://creativecommons.org/licenses/by/3.0/.
  */