docs: Add CONTRIBUTING.md

Author: lgatellier

CONTRIBUTING.md

@@ -0,0 +1,18 @@
+# Contributing
+
+You can contribue in multiple ways to this role :
+- Creating issues to warn about a bug or suggest a change
+- Improving role code and creating Pull Requests
+
+## Improving role code
+
+This role uses ansible-lint to ensure a minimum quality of its sources.
+
+Please [install pre-commit](https://pre-commit.com/#install), and install pre-commit hooks into your local repository :
+
+```shell
+pre-commit install
+```
+
+Now, ansible-lint will be executed against your commit content before validating commit.
+