Add files via upload - CONTRIBUTING.rst (#5138)

* Add files via upload

Adding of Contributing.rst file.

* Update CONTRIBUTING.rst

CONTRIBUTING.rst

+Contributions Guide
+===================
+
+We welcome contributions to the Arduino ESP32 project!
+
+How to Contribute
+-----------------
+
+Contributions to Arduino ESP32 - fixing bugs, adding features, adding documentation - are welcome. We accept contributions via `Github Pull Requests <https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/about-pull-requests>`_.
+
+Before Contributing
+-------------------
+
+Before sending us a Pull Request, please consider this list of points:
+
+* Is the contribution entirely your own work, or already licensed under an LGPL 2.1 compatible Open Source License? If not then we unfortunately cannot accept it.
+
+* Is the code adequately commented for people to understand how it is structured?
+
+* Is there documentation or examples that go with code contributions? 
+
+* Are comments and documentation written in clear English, with no spelling or grammar errors?
+
+* Example contributions are also welcome.
+
+* If the contribution contains multiple commits, are they grouped together into logical changes (one major change per pull request)? Are any commits with names like "fixed typo" `squashed into previous commits <https://eli.thegreenplace.net/2014/02/19/squashing-github-pull-requests-into-a-single-commit/>`_?
+
+* If you're unsure about any of these points, please open the Pull Request anyhow and then ask us for feedback.
+
+Pull Request Process
+--------------------
+
+After you open the Pull Request, there will probably be some discussion in the comments field of the request itself.
+
+Once the Pull Request is ready to merge, it will first be merged into our internal git system for in-house automated testing.
+
+If this process passes, it will be merged onto the public github repository.
+
+Legal Part
+----------
+
+Before a contribution can be accepted, you will need to sign our :doc:`contributor-agreement`. You will be prompted for this automatically as part of the Pull Request process.
+
+Related Documents
+-----------------
+
+.. toctree::
+    :maxdepth: 1
+
+        contributor-agreement