docs(tutorial/step9): formatted Unicode character line

Add tick and cross mark corresponding to their respective unicodes.

Author: exexzian

docs/content/tutorial/step_09.ngdoc

@@ -37,8 +37,7 @@ angular.module('phonecatFilters', []).filter('checkmark', function() {
 </pre>
 
 The name of our filter is "checkmark". The `input` evaluates to either `true` or `false`, and we
-return one of two unicode characters we have chosen to represent true or false (`\u2713` and
-`\u2718`).
+return one of the two unicode characters we have chosen to represent true (`\u2713` -> ✓) or false (`\u2718` -> ✘).
 
 Now that our filter is ready, we need to register the `phonecatFilters` module as a dependency for
 our main `phonecat` module.