docs($state): add note about default params

Author: tamlyn

src/state.js

@@ -883,7 +883,8 @@ function $StateProvider(   $urlRouterProvider,   $urlMatcherFactory) {
      *
      * @param {object=} params A map of the parameters that will be sent to the state, 
      * will populate $stateParams. Any parameters that are not specified will be inherited from currently 
-     * defined parameters. This allows, for example, going to a sibling state that shares parameters
+     * defined parameters. Only parameters specified in the state definition can be overridden, new 
+     * parameters will be ignored. This allows, for example, going to a sibling state that shares parameters
      * specified in a parent state. Parameter inheritance only works between common ancestor states, I.e.
      * transitioning to a sibling will get you the parameters for all parents, transitioning to a child
      * will get you all current parameters, etc.