Add grunt default task that explains the different commands.

Gruntfile.js

@@ -244,4 +244,17 @@ module.exports = function(grunt) {
     grunt.task.run('sass');
   });
   grunt.registerTask('default', ['scss']);
+
+  grunt.registerTask('default', function help() {
+    grunt.log.writeln(`\nHello! Here are your grunt command options:
+
+    - grunt less        = compile and compress all themes' LESS files to css.
+    - grunt scss        = compile and map all themes' SASS files to css.
+    - grunt lessdev     = compile and map all themes' LESS files to css.
+    - grunt watch:[cmd] = continuous monitor source files and run command when changes are detected.
+    - grunt watch:less
+    - grunt watch:scss
+    - grunt watch:lessdev
+    - grunt lessToSass  = transpile all LESS files to SASS.`);
+  });
 };