Update ngIf.js doc. Added missing description of ng-if behavior.

src/ng/directive/ngIf.js

@@ -16,6 +16,11 @@
  * case when this difference is significant is when using css selectors that rely on an element's
  * position within the DOM, such as the `:first-child` or `:last-child` pseudo-classes.
  *
+ * <div class="alert alert-warning">
+ * **Note:** Here is a list of values that ngIf will consider as a falsy value (case insensitive):<br />
+ * "f" / "0" / "false" / "no" / "n" / "[]"
+ * </div>
+ *
  * Note that when an element is removed using `ngIf` its scope is destroyed and a new scope
  * is created when the element is restored.  The scope created within `ngIf` inherits from
  * its parent scope using