get rid of containers.md (now part of README.md)

docs/containers.md

@@ -1,15 +0,0 @@
-1. Run `docker build -t y2z/monolith .` to create a Docker image
-
-2. Create a file named `monolith` which contains:
-```sh
-#!/bin/sh
-
-docker run --rm \
-    y2z/monolith \
-    monolith \
-    "$@"
-```
-3. Make the file executable (`chmod +x monolith`) and include it into your `$PATH`
-4. Now you should be able to run a containerized build of monolith like this:  
-`monolith -I https://github.com > document.html`
-