Update expandable.js

Author: norbert-farkas

src/features/expandable/js/expandable.js

@@ -117,7 +117,7 @@
                * @ngdoc event
                * @name rowExpandedStateChanged
                * @eventOf  ui.grid.expandable.api:PublicApi
-               * @description raised when cell editing is complete
+               * @description raised when row expanded or collapsed
                * <pre>
                *      gridApi.expandable.on.rowExpandedStateChanged(scope,function(row){})
                * </pre>