Allow configure experimental mode

Experimental mode allows to see logs of a swarm service,
e.g. docker service logs <service_id>
diff --git a/README.rst b/README.rst
index 4e13e9d..ea43d20 100644
--- a/README.rst
+++ b/README.rst
@@ -23,6 +23,7 @@
     docker:
       host:
         enabled: true
+        experimental: true
         insecure_registries:
           - 127.0.0.1
         log: