[doc] Fixes minor typo in MIGRATION.md

[Brett Rogerson (snypelife)]

Please prefix all TypeScript pull-requests with [Typescript]

What

Just a one word fix on the migration doc.

Checklist

• Contains customer facing changes? Including API/behavior changes
• Did you add sufficient unit test and/or integration test coverage for this PR?
  • If not, please explain why it is not required

References

JIRA:

Test & Review

Open questions / Follow-ups

[confluent-cla-assistant]

Please sign the Contributor License Agreement here before this PR can be approved.
❌ snypelife
_{Please push an empty commit if you would like to re-run the checks to verify CLA status for all contributors.}

[Robert Yokota (rayokota)]

Thanks Brett Rogerson (@snypelife) , LGTM

[Robert Yokota (rayokota)]

Brett Rogerson (@snypelife) , can you sign the CLA?

[Brett Rogerson (snypelife)]

Robert Yokota (@rayokota) hey sorry, I started to but wasn't exactly comfortable with providing that much PII.

I'm okay with this being closed and re-done. I was just reading the docs and figured I'd submit a patch real quick.

Thank you for reaching so quickly though 🙏