add Yaml snippet

Author: khash

documentation/weave_scope.md

@@ -2,12 +2,14 @@
 
 If you want to install weavescope on your Docker stack use the following last_thing hook.
 
+```yaml
 production: # Environment or your choice
   last_thing: # Importent to run the weavescope hook as the last thing during server deployment
     - snippet: cloud66/weave_scope # our weavescope snippet
       target: docker
       sudo: true
       execute: true
       run_on: all_servers #make sure weave scope is running on all servers and communicate to each other
-  
+```
+
 Warning: Weavescope will run on port 4040 which is not exposed to the outside world. If you want to access the UI change your firewall settings allowing traffic to port 4040. Make sure only you can access weavescope from your ip-address. With weavescope you can control all your running process and excute inside running containers. Take good care of those powers!