add param comment

Author: ajrice6713

bandwidth/voice/bxml/verbs/ring.py

@@ -20,6 +20,7 @@ def __init__(self, duration=None, answer_call=None):
         Initializes the Ring class with the duration parameter
 
         :param float duration: The time in seconds to ring
+        :param boolean answer_call: Whether or not to accept the incoming call while playing the ring
         """
         self.duration = duration
         self.answer_call = answer_call