Fix some documentation typos.

sleekxmpp/xmlstream/handler/callback.py

@@ -38,7 +38,7 @@ class Callback(BaseHandler):
             name     -- The name of the handler.
             matcher  -- A matcher object for matching stanza objects.
             pointer  -- The function to execute during callback.
-            threaded -- DEPRECATED. Remains only for backwards compatibility.
+            thread   -- DEPRECATED. Remains only for backwards compatibility.
             once     -- Indicates if the handler should be used only
                         once. Defaults to False.
             instream -- Indicates if the callback should be executed

sleekxmpp/xmlstream/handler/waiter.py

@@ -33,6 +33,14 @@ class Waiter(BaseHandler):
     """
 
     def __init__(self, name, matcher, stream=None):
+        """
+        Create a new Waiter.
+
+        Arguments:
+            name    -- The name of the waiter.
+            matcher -- A matcher object to detect the desired stanza.
+            stream  -- Optional XMLStream instance to monitor.
+        """
         BaseHandler.__init__(self, name, matcher)
         self._payload = queue.Queue()