New guidelines.

Author: JC5

.github/contributing.md

@@ -1,3 +1,5 @@
-# [Contributing guidelines](https://docs.firefly-iii.org/firefly-iii/support/#contributing-code)
+# Contributing guidelines
 
-[Contributing guidelines](https://docs.firefly-iii.org/firefly-iii/support/#contributing-code)
+This repository is part of "Firefly III", by being either a main repository for code, a supporting repository with guidelines and documentation, or a repository with tools and secondary code.
+
+The [contribution guidelines](https://docs.firefly-iii.org/explanation/contributing/) for this repository are the same as they are for ALL Firefly III related repositories, and they can be found in [the Firefly III documentation](https://docs.firefly-iii.org/explanation/contributing/).