Add missing import to auth example.

rossigee · rossigee · commit 46a9e92f91c9 · 2017-01-25T12:00:14.000+07:00
diff --git a/README.md b/README.md
@@ -328,6 +328,7 @@ you can use a special handler to set the Authorization header.
 
 ```python
 from prometheus_client import CollectorRegistry, Gauge, push_to_gateway
+from prometheus_client.handlers.basic_auth import handler as basic_auth_handler
 import os
 
 def my_auth_handler(url, method, timeout, headers, data):
