Add network documentation

[ci skip]

README.md

@@ -19,6 +19,7 @@ This is meant to be used as a [Drone plugin](http://plugins.drone.io/).
 - **host** (default: `swarm.autonomic.zone`): Host to deploy to (don't include `ssh://`)
 - **port** (default: `222`): SSH port to connect to
 - **user** (default: `drone`): System user to connect via SSH with
+- **networks** (default:): Try and auto-create these networks first
 
 ### Dangerous options, unwise outside CI
 
@@ -41,6 +42,11 @@ steps:
       stack: mystack
       deploy_key:
         from_secret: drone_deploy_key
+      networks:
+        - proxy
+        - mail
+      environment:
+        DOMAIN: test.example.com
 ```
 
 ## Publishing