Merge pull request #2304 from hannseman/swarm-join-listen_addr

Document correct listen_addr default on join swarm

Author: chris-crone

docker/api/swarm.py

@@ -205,7 +205,7 @@ def join_swarm(self, remote_addrs, join_token, listen_addr='0.0.0.0:2377',
             listen_addr (string): Listen address used for inter-manager
                 communication if the node gets promoted to manager, as well as
                 determining the networking interface used for the VXLAN Tunnel
-                Endpoint (VTEP). Default: ``None``
+                Endpoint (VTEP). Default: ``'0.0.0.0:2377``
             advertise_addr (string): Externally reachable address advertised
                 to other nodes. This can either be an address/port combination
                 in the form ``192.168.1.1:4567``, or an interface followed by a