chore: Fix typos

[Subash-Lamichhane]

Before submitting a pull request, please take a look at our
Contributing guidelines and verify:

• If you've added code that should be tested, please add tests.
• Ensure your code lints and the test suite passes (yarn lint) & (yarn test).

Fixed multiple typos from "CONTRIBUTING.md" and "MIGRATION.md"
commited -> committed
depracted -> available
seperate -> separate
returing -> returning

[lforst]

Thanks!

[AbhiPrasad]

Thank you @Subash-Lamichhane!