Readme should use new docker compose format instead of the old one

Signed-off-by: Callum Rogers <callumrogers@hotmail.co.uk>

README.md

@@ -22,16 +22,17 @@ they can be run together in an isolated environment:
 
 A `docker-compose.yml` looks like this:
 
-    web:
+    version: '2'
-      build: .
+
-      ports:
+    services:
-       - "5000:5000"
+      web:
-      volumes:
+        build: .
-       - .:/code
+        ports:
-      links:
+         - "5000:5000"
-       - redis
+        volumes:
-    redis:
+         - .:/code
-      image: redis
+      redis:
+        image: redis
 
 For more information about the Compose file, see the
 [Compose file reference](https://github.com/docker/compose/blob/release/docs/compose-file.md)