[DOCS] Move changelog instructions to contribution steps

[jtpham4]

What does this PR do?

Steps for generating changelog doc/topics/development/changelog.rst are combined into doc/topics/development/contributing.rst`

What issues does this PR fix or reference?

References: #59854

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• [ ] Docs
• [ ] Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• [N/A ] Tests written/updated

Commits signed with GPG?

No

Please review Salt's Contributing Guide for best practices.

See GitHub's page on GPG signing for more information about signing commits with GPG.

[welcome[bot]]

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[Ch3LL]

@jtpham4 are you able to come back to this and fix some of the feedback i submitted?

[Ch3LL]

bump ^

[Ch3LL]

Closing due to inactivity. Please let me know if I need to re-open or open a new PR that includes the feedback.