fix(README): add subsection usage

README.md

@@ -3,9 +3,12 @@
 [![Build Status](https://travis-ci.com/volker-raschek/build-image.svg?branch=master)](https://travis-ci.com/volker-raschek/build-image)
 [![Docker Pulls](https://img.shields.io/docker/pulls/volkerraschek/build-image)](https://hub.docker.com/r/volkerraschek/build-image)
 
-This project contains only files to build a build container image.
+This project, hosted on [github](https://github.com/volker-raschek/build-image),
+contains only files to build a build container image.
 
-## golang
+## Usage
+
+### golang
 
 To use this image for building golang applications execute this in your root
 folder of your go project.
@@ -18,7 +21,7 @@ $ docker run \
       go build
 ```
 
-## rust
+### rust
 
 If you want to compile instead go rust sourcecode, than you can do it similar to the golang example.