WIP | Add CONTRIBUTING

Author: jrfnl

CONTRIBUTING.md

@@ -0,0 +1,40 @@
+# Contributing to the PHP_CodeSniffer documentation
+
+## PHP_CodeSniffer Wiki
+
+For now, the documentation for the PHP_CodeSniffer project is available via the [project Wiki](https://github.com/PHPCSStandards/PHP_CodeSniffer/wiki).
+
+### Contributing to the Wiki
+
+If you would like to improve the documentation:
+1. Fork this repo.
+2. Create a new branch off the `main` branch.
+3. Make your changes. The Wiki source files are in the `/wiki` subdirectory.
+4. Commit your changes with a meaningful commit message.
+5. Push your changes to your fork.
+6. Submit a pull request from your fork to this repository.
+
+When in doubt, open an issue first to discuss your change proposal.
+
+### How does the wiki get updated ?
+
+* The source of the Wiki was imported into this repository to maintain the commit history.
+* A [GitHub Actions workflow](https://github.com/PHPCSStandards/PHP_CodeSniffer-documentation/blob/main/.github/workflows/publish-wiki.yml) was added to automatically push changes made in the Wiki files to the upstream Wiki repo.
+* Prior to pushing the changes, the workflow will make various changes to the files:
+    * Replace `<!-- START doctoc --> <!-- END doctoc -->` placeholders with a Table of Contents for the page in Markdown.
+    * Replace `{{ .... }}` CLI output placeholders with actual CLI output.
+        The code samples used for this can be found in the `build/wiki/code-samples` directory.
+
+### Guidelines
+
+* Always use fully qualified links. This ensures that the links will work when pages are viewed/edited in this repo, as well as when the pages are viewed from the PHPCS wiki.
+
+
+### Frequently Asked Questions
+
+#### Why not make the Wiki publicly editable ?
+
+Publicly editable Wiki pages for big projects get vandalized pretty often and we don't want to risk this type of vandalism leading to users getting incorrect information.
+
+As a secondary reason, there are parts of the wiki (especially the output examples) which were pretty out of date.
+By having the wiki source in this repo, it allows for automating certain updates which would otherwise have to be done manually.

README.md

@@ -8,3 +8,8 @@ The intention is for that website to be a GitHub Pages/Jekyll site, but we'll ne
 In the mean time, the documentation for the PHP_CodeSniffer project is available via the [project Wiki](https://github.com/PHPCSStandards/PHP_CodeSniffer/wiki) and made publicly editable via this repository.
 
 _This is an interim solution and the intention is to eventually migrate the wiki documentation to the website._
+
+
+## Want to contribute ?
+
+Have a look at the [CONTRIBUTING guide](CONTRIBUTING.md).