update README

Author: tknerr

README.md

@@ -19,7 +19,8 @@ For the Chef-based equivalent of it, see https://github.com/Zuehlke/linux-develo
 
 These are the main tools included in this developer VM:
 
- * [VSCode](https://code.visualstudio.com/) - as a general purpose (code) editor
+ * [VSCode](https://code.visualstudio.com/) - as a general purpose (code) editor, e.g. for updating the Ansible roles when working from within the developer VM
+ * [Docker](https://www.docker.com/) - as a general purpose container runtime, e.g. for building your applications with a dockerized toolchain
 
 Apart from the above, the following tools are used to set up and maintain this developer VM: