e2e guide: fix /claim response

supporting-docs/guides/2016-10-18-e2e_implementation.rst

@@ -654,6 +654,7 @@ This will return a result as follows:
 .. code:: json
 
   {
+    "one_time_keys": {
       "<user id>": {
         "<device_id>": {
           "signed_curve25519:<key_id>": {
@@ -669,6 +670,7 @@ This will return a result as follows:
       },
       ...
     }
+  }
 
 The client should first check the signatures on the signed key objects. As with
 checking the signatures on the device keys, it should remove the ``signatures``