docs: Add contribution guide

[mbfakourii]

Pull Request

• Report security issues confidentially.
• Any contribution is under this license.
• Link this pull request to an issue.

Issue

Closes: #917

Approach

Add CONTRIBUTING.md

Tasks

• Add tests
• Add changes to documentation (guides, repository pages, code comments)

[parse-github-assistant]

Thanks for opening this pull request!

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (a836d8e) 38.55% compared to head (4e7ba14) 38.55%.

❗ Current head 4e7ba14 differs from pull request most recent head 835a1db. Consider uploading reports for the commit 835a1db to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #916   +/-   ##
=======================================
  Coverage   38.55%   38.55%           
=======================================
  Files          59       59           
  Lines        3328     3328           
=======================================
  Hits         1283     1283           
  Misses       2045     2045           

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[mtrezza]

Looks good!