Add challenges #2 and #3

3/docker-compose.yml

@@ -0,0 +1,11 @@
+--- 
+# TIP: Where can we see a list of valid image repos (names)?
+# TIP: Check on git.autonomic.zone -- don't peek at challenge 1 or 2!
+
+services:
+  app:
+    image: git.autonomic.zone/autonomic-cooperative/disco:0.1.0
+    ports:
+      - 8000:80
+    environment:
+      - CHALLENGE=3