Add Instructions on how to use project

README.md

@@ -6,11 +6,41 @@ Collection of Dockerfiles created to build & pack various tools.
 <br>
 
 <!-- TOC -->
-- [1. Tools](#1-tools)
+- [1. How to use](#1-how-to-use)
+    - [1.1. CLI](#11-cli)
+- [2. Tools](#2-tools)
 <!-- /TOC -->
 
 <br>
 
-# 1. Tools
+# 1. How to use
+
+Run the build-script `script/build.sh` with the path to the tool you want to build.
+
+<br>
+
+The docker-image will be tagged with `default` and the detected version/commit-hash.
+
+You can add more tags or change the existing tag-naming-scheme using the environment-variable `TAG`.
+
+<br>
+
+## 1.1. CLI
+
+`script/build.sh <toolPath> [extra-args for docker build ..]`
+
+<br>
+
+### 1.1.1. Environment-Variables
+
+Variable    | Description                       | Default
+-|-|-
+`TAG`       | Tag for Docker-building           | `TAGPREFIX` + `NAME`
+`TAGPREFIX` | Set a prefix to the default-tag   | -
+`NAME`      | Change the name used in the tag   | *FolderName*
+
+<br>
+
+# 2. Tools
 
 Nothing yet