Fix the Sphinx auto generation

doc/python/sphinx/grpc.rst

@@ -40,7 +40,7 @@ Create Client Credentials
 .. autofunction:: access_token_call_credentials
 .. autofunction:: composite_call_credentials
 .. autofunction:: composite_channel_credentials
-.. autofunction:: local_channel_credentials
+.. autofunction:: local_channel_credentials(local_connect_type=grpc.LocalConnectionType.LOCAL_TCP)
 
 
 Create Server
@@ -55,7 +55,7 @@ Create Server Credentials
 .. autofunction:: ssl_server_credentials
 .. autofunction:: ssl_server_certificate_configuration
 .. autofunction:: dynamic_ssl_server_credentials
-.. autofunction:: local_server_credentials
+.. autofunction:: local_server_credentials(local_connect_type=grpc.LocalConnectionType.LOCAL_TCP)
 
 
 Local Connection Type