Add eslint instructions to getting started

[yepitschunked]

Summary

ESLint is used in almost every project, but the docs don't talk about setting it up. This Stack Overflow question has 188k views: https://stackoverflow.com/questions/31629389/how-to-use-eslint-with-jest

The top answer links to docs from eslint-plugin-jest, when these instructions should just be part of Jest's docs.

Test plan

Docs change

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• ✅ login: SimenB / name: Simen Bekkhus (d3fb20c, 5c23bbf, a8bb8bd, fe25da1, d98b0a2, ba9d784, 4fe7a29, 50ccff1)

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[SimenB]

Thanks! Can you add this to all versions of the docs?

[SimenB]

👍

[yepitschunked]

@SimenB I had to fix some issues with prettier, it seems like automerge got disabled as a result - can you take another look?

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This PR is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 30 days.

[SimenB]

thanks!

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
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