Add challenges #2 and #3

2/docker-compose.yml

@@ -0,0 +1,12 @@
+--- 
+# TIP: Where can we see a list of valid image tags (versions?).
+# TIP: Check on git.autonomic.zone -- don't peek at challenge 1!
+
+services:
+  app:
+    image: git.autonomic.zone/autonomic-cooperative/docker-debugging-disco:0.2.0
+    ports:
+      - 8000:80
+    environment:
+      - CHALLENGE=2
+