rename HTML5 validation Grunt task since it checks the examples too

Gruntfile.js

@@ -166,10 +166,10 @@ module.exports = function(grunt) {
   grunt.loadNpmTasks('browserstack-runner');
 
   // Docs HTML validation task
-  grunt.registerTask('validate-docs', ['jekyll', 'validation']);
+  grunt.registerTask('validate-html', ['jekyll', 'validation']);
 
   // Test task.
-  var testSubtasks = ['jshint', 'qunit', 'validate-docs'];
+  var testSubtasks = ['jshint', 'qunit', 'validate-html'];
   // Only run BrowserStack tests under Travis
   if (process.env.TRAVIS) {
     // Only run BrowserStack tests if this is a mainline commit in twbs/bootstrap, or you have your own BrowserStack key