Update README.md with maintenance notice

[benjaminmodayil]

Adds a maintenance notice with a link to this PR. It would save a lot of teams time in re-development if they knew up front that this repository isn't actively maintained. Our team had/has to backtrack on certain components in our design system/project that we recently made because we didn't know the project wasn't actively maintained.

• Use a meaningful title for the pull request. Include the name of the package modified.
• Test the change in your own code (Compile and run).
• Ensure formatting is consistent with the project's Prettier configuration.
• Add documentation to support any new features.

This pull request:

• Updates documentation or example code

[changeset-bot]

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Latest commit: 3eeba44

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