[DOC] Updated readme and contributing files (bp #1284)

[mergify]

This is an automated backport of pull request #1284 done by Mergify

Cherry-pick of 6a64398 has failed:

On branch mergify/bp/rls/2021-gold-mnt/pr-1284
Your branch is up to date with 'origin/rls/2021-gold-mnt'.

You are currently cherry-picking commit 6a6439801.
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Changes to be committed:

	modified:   CONTRIBUTING.md

Unmerged paths:
  (use "git add <file>..." to mark resolution)

	both modified:   README.md

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