Merge pull request #1089 from q0rban/add-contributing-md

Add a CONTRIBUTING.md file for n00bs like me

Author: yosifkit

CONTRIBUTING.md

@@ -0,0 +1,15 @@
+# Contributing to this repository
+
+1. Don't edit the Dockerfiles directly. They are generated using templates.
+2. Make any changes to the `*.template` files in the root of the repository.
+3. Make sure you've checked the [Requirements](#requirements) below.
+4. Run the `./apply-templates.sh` script after making your changes.
+5. Once complete, (review and) commit all changes to the templates and Dockerfiles.
+
+## Requirements
+
+You will need the following software packages to run the [`./apply-templates.sh`](/apply-templates.sh) script.
+
+- [GNU awk](https://www.gnu.org/software/gawk/) available as `gawk`.
+- [`jq`](https://stedolan.github.io/jq/)
+- A recent version of Bash