fix(docs): include short words in keywords

Short words like $q are now searchable.

Closes #967

Author: mhevery

docs/src/ngdoc.js

@@ -54,7 +54,7 @@ Doc.prototype = {
     function extractWords(text) {
       var tokens = text.toLowerCase().split(/[,\.\`\'\"\#\s]+/mg);
       tokens.forEach(function(key){
-        var match = key.match(/^(([\$\_a-z]|ng\:)[\w\_\-]{2,})/);
+        var match = key.match(/^(([\$\_a-z]|ng\:)[\w\_\-]+)/);
         if (match){
           key = match[1];
           if (!keywords[key]) {