docs(ngHide): use proper selector when overriding the CSS

The animation selector gives the default styles greater specificity that
should be matched when overriding.

Closes #10902
Closes #10913

Author: iangreenleaf

src/ng/directive/ngShowHide.js

@@ -40,10 +40,11 @@ var NG_HIDE_IN_PROGRESS_CLASS = 'ng-hide-animate';
  *
  * By default, the `.ng-hide` class will style the element with `display: none!important`. If you wish to change
  * the hide behavior with ngShow/ngHide then this can be achieved by restating the styles for the `.ng-hide`
- * class in CSS:
+ * class CSS. Note that the selector that needs to be used is actually `.ng-hide:not(.ng-hide-animate)` to cope
+ * with extra animation classes that can be added.
  *
  * ```css
- * .ng-hide {
+ * .ng-hide:not(.ng-hide-animate) {
  *   /* this is just another form of hiding an element */
  *   display: block!important;
  *   position: absolute;