Simplify docker-compose.yml example

Remove `container_name` as not required

README.md

@@ -39,10 +39,10 @@ This image is based on the nginx:alpine image. Use this image to fully support H
 
 ```yaml
 version: '2'
+
 services:
   nginx-proxy:
     image: jwilder/nginx-proxy
-    container_name: nginx-proxy
     ports:
       - "80:80"
     volumes:
@@ -50,7 +50,6 @@ services:
 
   whoami:
     image: jwilder/whoami
-    container_name: whoami
     environment:
       - VIRTUAL_HOST=whoami.local
 ```