Add some documentation for Abbreviation.

--HG--
extra : rebase_source : cdc495381db878c2e7bef2a817e40c2d2a196075

common/content/quickmarks.js

@@ -35,7 +35,7 @@ var QuickMarks = Module("quickmarks", {
      * Returns a list of QuickMarks associates with the given URL.
      *
      * @param {string} url The url to find QuickMarks for.
-     * @return {[string]}
+     * @returns {[string]}
      */
     find: function find(url) {
         let res = [];