Add v3 example

Same example as docker-compose.yaml but with 3 in the version name.

Needed for 1.0.0 blog post!

examples/docker-compose-v3.yaml

@@ -0,0 +1,24 @@
+version: "3"
+
+services:
+
+  redis-master:
+    image: gcr.io/google_containers/redis:e2e 
+    ports:
+      - "6379"
+
+  redis-slave:
+    image: gcr.io/google_samples/gb-redisslave:v1
+    ports:
+      - "6379"
+    environment:
+      - GET_HOSTS_FROM=dns
+
+  frontend:
+    image: gcr.io/google-samples/gb-frontend:v4
+    ports:
+      - "80:80"
+    environment:
+      - GET_HOSTS_FROM=dns
+    labels:
+      kompose.service.type: LoadBalancer