Moved CONTRIBUTING.md to root dir

[vickylaram]

Regarding issue #1608

PR checklist

• This comment contains a description of changes (with reason)
• CHANGELOG.md is updated
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated

[piotr-faba-ardigen]

Hi @vickylaram.
You'll need to modify CHANGELOG.md with reasonable change description, so that the automatic check passes

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.84%. Comparing base (9eac5e9) to head (eb7117d).
Report is 94 commits behind head on dev.

❗ Current head eb7117d differs from pull request most recent head eb89284. Consider uploading reports for the commit eb89284 to get more accurate results

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