Fix broken links in API doc

Author: dmurvihill

API.md

@@ -12,9 +12,9 @@ Only `MockFirebase` methods are included here. For details on normal Firebase AP
   - [`fakeEvent(event [, key] [, data] [, previousChild] [, priority])`](#fakeeventevent--key--data--previouschild--priority---ref)
   - [`getFlushQueue()`](#getflushqueue---array)
 - [Auth](#auth)
-  - [`changeAuthState(user)`](#changeauthstateauthdata---undefined)
-  - [`getUserByEmail(email)`](#getemailuseremail---objectnull)
-  - [`getUser(uid)`](#getemailuseremail---objectnull)
+  - [`changeAuthState(user)`](#changeauthstateuser---undefined)
+  - [`getUserByEmail(email)`](#getuserbyemailemail---promiseobject)
+  - [`getUser(uid)`](#getuseruid---promiseobject)
 - [Server Timestamps](#server-timestamps)
   - [`setClock(fn)`](#firebasesetclockfn---undefined)
   - [`restoreClock()`](#firebasesetclockfn---undefined)