chore: add contribution guidelines

Author: n0rfas

CONTRIBUTING.md

@@ -0,0 +1,21 @@
+## How to contribute to git-analytics
+
+#### **Did you find a bug?**
+
+- **Ensure the bug was not already reported** by searching on GitHub under [Issues](https://github.com/n0rfas/git-analytics/issues).
+
+- If you're unable to find an open issue addressing the problem, [open a new one](https://github.com/n0rfas/git-analytics/issues/new?template=bug_report.md). Be sure to include a **title and clear description**, as much relevant information as possible, and a **code sample** or an **executable test case** demonstrating the expected behavior that is not occurring.
+
+#### **Did you write a patch that fixes a bug?**
+
+- Open a new GitHub pull request with the patch.
+
+- Ensure the PR description clearly describes the problem and solution. Include the relevant issue number if applicable.
+
+#### **Do you intend to add a new feature or change an existing one?**
+
+- Suggest your change in the [Github Discussions](https://github.com/n0rfas/git-analytics/discussions) and start writing code.
+
+- Do not open an issue on GitHub until you have collected positive feedback about the change. GitHub issues are primarily intended for bug reports and fixes.
+
+Thanks!