Add note about ghost-cli not intended to work

Mention ghost-cli is not working out of the box, refer to @acburdine comment explaining why on https://github.com/docker-library/ghost/issues/156

ghost/content.md

@@ -84,6 +84,10 @@ $ docker exec <container-id> node --version
 v6.11.2
 ```
 
+## Note about ghost-cli
+
+While the docker images do have ghost-cli available and do use some of its commands to set up the base Ghost image, many of the other ghost-cli commands won't work correctly, and really aren't designed/intended to. For more info see [Why sudo is not packed and ghost-cli wont work out of the box](https://github.com/docker-library/ghost/issues/156#issuecomment-428159861)
+
 ## %%STACK%%
 
 Run `docker stack deploy -c stack.yml %%REPO%%` (or `docker-compose -f stack.yml up`), wait for it to initialize completely, and visit `http://swarm-ip:8080`, `http://localhost:8080`, or `http://host-ip:8080` (as appropriate).