docs(search): set minimum length to 2

With the minimum search length set to 3, it was not possible to search for `$q`.
Changing this to 2 fixes that without really upsetting the search display, since we
only display the first 40 API and 14 non-API items anyway.

Closes angular#3078

Author: petebacondarwin

docs/app/src/search.js

@@ -8,7 +8,7 @@ angular.module('search', [])
   }
 
   $scope.search = function(q) {
-    var MIN_SEARCH_LENGTH = 3;
+    var MIN_SEARCH_LENGTH = 2;
     if(q.length >= MIN_SEARCH_LENGTH) {
       var results = docsSearch(q);
       var totalAreas = 0;