docs(ngAnimate): fix typos in JS and CSS selector

Closes #12203

Author: yichaowang

src/ngAnimate/module.js

@@ -655,7 +655,7 @@
  * ngModule.directive('greetingBox', ['$animate', function($animate) {
  *   return function(scope, element, attrs) {
  *     attrs.$observe('active', function(value) {
- *       value ? $animate.addClass(element, 'on') ? $animate.removeClass(element, 'on');
+ *       value ? $animate.addClass(element, 'on') : $animate.removeClass(element, 'on');
  *     });
  *   });
  * }]);
@@ -666,7 +666,7 @@
  *
  * ```css
  * /* normally we would create a CSS class to reference on the element */
- * [greeting-box].on { transition:0.5s linear all; background:green; color:white; }
+ * greeting-box.on { transition:0.5s linear all; background:green; color:white; }
  * ```
  *
  * The `$animate` service contains a variety of other methods like `enter`, `leave`, `animate` and `setClass`. To learn more about what's