docs: update contribution merge guide

[mtrezza]

New Pull Request Checklist

• I am not disclosing a vulnerability.
• I am creating this PR in reference to an issue.

Issue Description

Update contribution guide PR and merge instructions

Related issue: #n/a

Approach

TODOs before merging

[parse-github-assistant]

Thanks for opening this pull request!

• ❌ Please check all required checkboxes at the top, otherwise your pull request will be closed.

• ⚠️ Remember that a security vulnerability must only be reported confidentially, see our Security Policy. If you are not sure whether the issue is a security vulnerability, the safest way is to treat it as such and submit it confidentially to us for evaluation.

[parseplatformorg]

🎉 This change has been released in version 5.0.0-beta.1

[parseplatformorg]

🎉 This change has been released in version 5.0.0