FED-3009 Update migration guide with required props codemod instructions

[greglittlefield-wf]

Dependent PR

Depends on codemod within https://github.com/Workiva/over_react_codemod/pull/290 being merged and released.

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Motivation

Now that the null safety required props codemod (https://github.com/Workiva/over_react_codemod/pull/290) available, we need to update instructions within the null safety migration guide.

Changes

• Add instructions for new codemod
• Remove placeholder about waiting for codemod to be complete

Release Notes

Review

See CONTRIBUTING.md for more details on review types (+1 / QA +1 / +10) and code review process.

Please review:

QA Checklist

• [ ] Tests were updated and provide good coverage of the changeset and other affected code
• [ ] Manual testing was performed if needed
  • [ ] Steps from PR author:
    • Links aren't broken
  • [ ] Anything falling under manual testing criteria outlined in CONTRIBUTING.md

Merge Checklist

While we perform many automated checks before auto-merging, some manual checks are needed:

• [ ] A Frontend Frameworks Design member has reviewed these changes
• [ ] There are no unaddressed comments - this check can be automated if reviewers use the "Request Changes" feature
• [ ] For release PRs - Version metadata in Rosie comment is correct

[aviary-wf]

Security Insights

No security relevant content was detected by automated scans.

Action Items

• Review PR for security impact; comment "security review required" if needed or unsure

• Verify aviary.yaml coverage of security relevant code

  Questions or Comments? Reach out on Slack: #support-infosec.

[greglittlefield-wf]

@Workiva/release-management-p