fix trivial format

[gogotanaka]

Request Type: docs

How to reproduce:

Component(s):

Impact: small

Complexity: small

This issue is related to:

Detailed Description:

While this may be no big deal, I found some issues format style.

"CHANGELOG.md" contain 2-space indent and tab indent.

"CONTRIBUTING.md" contain wasted spaces.

Other Comments:

Truth be told, I want to do more great things for ruby, but because my ability clumsy yet, start with these ...!

[mary-poppins]

Thanks for the PR! Please check the items below to help us merge this faster. See the contributing docs for more information.

• Uses the issue template (#6407)

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Then, update the pull request with git push -f.

Thanks again for your help!

[mary-poppins]

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[petebacondarwin]

@gogotanaka - thanks for the PR. The extra indents were actually important as they indicated that the block was code. You can see this by checking the markdown rendered view of the CHANGELOG file after your change. I fixed this in any case by using code fences (```)