chore: add contributions policy

Signed-off-by: tdruez <tdruez@aboutcode.org>

Author: tdruez

CONTRIBUTING.md

@@ -0,0 +1,45 @@
+# Contributing to DejaCode
+
+Thank you for your interest in contributing to AboutCode projects.
+Please **read the following guidelines carefully before submitting a pull request**.
+
+## Pull request rules
+
+- **Attach your PR to an existing issue.** Discuss the approach and implementation
+  details in the issue first, before writing any code. Please note that if the issue
+  has already been assigned to someone else, you are welcome to comment on it, but it
+  would be best to contribute code in such a case only if you are invited to do so.
+
+- **You must fully understand your code changes** and be able to explain them
+  clearly. If you cannot walk a reviewer through your changes, the PR will not
+  be accepted.
+
+- **Write your own descriptions, comments, and documentation.** All written
+  content in a PR must be authored by a human.
+
+- **Disclose any AI usage.** If any part of your contribution was generated or
+  assisted by AI, you must disclose this and specify the tools used.
+
+- **Include tests.** Any code change or addition must be accompanied by proper
+  unit tests. Untested code will not be merged.
+
+**Any PR that violates these rules will be closed.**
+
+## Pull request tips
+
+To maximize your chances of a successful contribution:
+
+- **Keep changes focused.** Address only what the issue requires. Do not bundle
+  unrelated changes together.
+
+- **Be patient.** Do not solicit maintainers for a review.
+
+- **Remember:** project maintainers have no interest in reviewing code
+  generated by machines.
+
+- **Do not make structural changes** to the codebase such as adding type hints.
+
+## Ways to Contribute
+
+See https://dejacode.readthedocs.io/en/latest/contributing.html for more ways to 
+contribute.

CONTRIBUTING.rst

@@ -29,6 +29,12 @@ The DejaCode documentation also provides:
 - how to customize your own workflows and reports.
 - guidelines for contributing to code development.
 
+Contributing
+============
+
+Thank you for your interest in contributing to AboutCode projects.
+Please `read the following guidelines carefully <https://github.com/aboutcode-org/dejacode/blob/main/CONTRIBUTING.md>`_  before getting started.
+
 Build and tests status
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