added the listener url to the documentation

README.md

@@ -39,6 +39,7 @@ format={ "loggerName":"%(name)s", "functionName":"%(funcName)s", "lineNo":"%(lin
  - Number of logs to keep in buffer before draining
  - Time to wait before draining, regardless of the previouse setting
  - Log type, for searching in logz.io (defaults to "python")
+ - Logz.io Listener address (defaults to "https://listener.logz.io:8071/")
 
 #### Code Example
 ```python
@@ -82,6 +83,7 @@ LOGGING = {
             'level': 'INFO',
             'formatter': 'json',
             'token': 'token',
+            'url': 'https://listener.logz.io:8071/'
             'logs_drain_count': 10,
             'logs_drain_timeout': 5,
             'logzio_type': "django"
@@ -102,6 +104,7 @@ LOGGING = {
 ```
 *Change*
 - token - Your logzio token
+- url - Logz.io Listener address
 - logs_drain_count - Number of logs to keep in buffer before draining
 - logs_drain_timeout - Time to wait before draining, regardless of the previouse setting
 - logzio_type - Log type, for searching in logz.io (defaults to "python")