Create CONTRIBUTING.md

just copy-pasted the rst from

   https://b3yc0d3.github.io/rule34Py/dev/contributing.html

and converted it to markdown

Author: b3yc0d3

CONTRIBUTING.md

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+# Contributing
+
+Thanks for taking an interest in contributing to the rule34Py project!
+
+* This project's **canonical upstream** is at https://github.com/b3yc0d3/rule34Py.
+* File **bugs**, **enhancement requests**, and other **issues** to the GH issue tracker at https://github.com/b3yc0d3/rule34Py/issues.
+* See the [Developer Guide](https://b3yc0d3.github.io/rule34Py/dev/developer-guide.html) for information about how to **build** this project from source and run tests.
+
+
+## Submitting Changes
+
+#. Base your development branch off of the [upstream](https://github.com/b3yc0d3/rule34Py/tree/develop) ``develop`` reference.
+
+#. Before committing your changes, run the **project linter** using ``make``. It will use the ``ruff`` to lint all the project sources.
+
+    .. code-block:: bash
+
+        poetry install  # Optional, if you have not done it previously.
+        make lint
+
+    Fix or respond to any findings in the linter.
+
+#. Run the project's test suite against your changes. Ensure that all tests pass.
+
+    .. code-block:: bash
+
+        poetry install  # Optional, if you have not done it previously.
+        make check
+
+#. Write a good commit message. If you are unsure of how, [this cbeams article](https://cbea.ms/git-commit/) gives reasonable suggestions. Commit your changes.
+
+#. Fork the canonical upstream repository on github. \[[GitHub Docs](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/fork-a-repo)\]
+
+#. Push your development branch to your own fork. [Open a new Pull Request](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/creating-a-pull-request-from-a-fork) against the upstream `develop` ref.
+
+#. Submit your PR. Respond to any PR build failures or feedback from the maintainers.