Update guides to use v2 config format.

Signed-off-by: Daniel Nephin <dnephin@docker.com>

docs/django.md

@@ -72,6 +72,8 @@ and a `docker-compose.yml` file.
 
 9. Add the following configuration to the file.
 
+        version: '2'
+        services:
           db:
             image: postgres
           web:
@@ -81,7 +83,7 @@ and a `docker-compose.yml` file.
               - .:/code
             ports:
               - "8000:8000"
-          links:
+            depends_on:
               - db
 
     This file defines two services: The `db` service and the `web` service.

docs/gettingstarted.md

@@ -95,13 +95,16 @@ Define a set of services using `docker-compose.yml`:
 1. Create a file called docker-compose.yml in your project directory and add
    the following:
 
+
+        version: '2'
+        services:
           web:
             build: .
             ports:
              - "5000:5000"
             volumes:
              - .:/code
-          links:
+            depends_on:
              - redis
           redis:
             image: redis

docs/rails.md

@@ -43,6 +43,8 @@ You'll need an empty `Gemfile.lock` in order to build our `Dockerfile`.
 
 Finally, `docker-compose.yml` is where the magic happens. This file describes the services that comprise your app (a database and a web app), how to get each one's Docker image (the database just runs on a pre-made PostgreSQL image, and the web app is built from the current directory), and the configuration needed to link them together and expose the web app's port.
 
+    version: '2'
+    services:
       db:
         image: postgres
       web:
@@ -52,7 +54,7 @@ Finally, `docker-compose.yml` is where the magic happens. This file describes th
           - .:/myapp
         ports:
           - "3000:3000"
-      links:
+        depends_on:
           - db
 
 ### Build the project

docs/wordpress.md

@@ -41,12 +41,14 @@ and WordPress.
 Next you'll create a `docker-compose.yml` file that will start your web service
 and a separate MySQL instance:
 
+    version: '2'
+    services:
       web:
         build: .
         command: php -S 0.0.0.0:8000 -t /code
         ports:
           - "8000:8000"
-      links:
+        depends_on:
           - db
         volumes:
           - .:/code