chore(readme): Update the React 18 upgrade docs

[lukaselmer]

What:

Update the React 18 upgrade docs

Why:

To make it easier to upgrade to React 18

How:

To document what the developer can do to upgrade to React 18

Checklist:

• Documentation updated
• Tests
• Ready to be merged
• Added myself to contributors table

I tested it manually on my React project

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[joshuaellis]

I personally find that this to be confusing & a little superfluous... I think the current description is fine and we probably don't want to inflate the docs further.

[lukaselmer]

I personally find that this to be confusing & a little superfluous... I think the current description is fine and we probably don't want to inflate the docs further.

I would have helped me. And it seems I'm not the first it would have helped #832 #826 #842. But if you think it doesn't help others then feel free to close it.

[mindplay-dk]

I spent almost a full day pulling my hair out, as all the tests broke after upgrading - error messages, as always, unhelpful.

This may be totally obvious to people who've been working with testing-library for a while - I just dropped into a project and was asked to upgrade react to 18, and I've never used testing-library, so I don't have that context.

I had to read through numerous long issues, to finally find the explanation at the end of a long issue thread, pointing to this PR.

There's no reason for anyone else to go through that pain - I suggest you get this merged right away.

[lukaselmer]

I spent almost a full day pulling my hair out, as all the tests broke after upgrading - error messages, as always, unhelpful.

This may be totally obvious to people who've been working with testing-library for a while - I just dropped into a project and was asked to upgrade react to 18, and I've never used testing-library, so I don't have that context.

I had to read through numerous long issues, to finally find the explanation at the end of a long issue thread, pointing to this PR.

There's no reason for anyone else to go through that pain - I suggest you get this merged right away.

Couldn't agree more :)

[codecov]

Codecov Report

Merging #841 (88ecaf0) into main (7a6e935) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main      #841   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           15        15           
  Lines          245       245           
  Branches        34        34           
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  Hits           245       245           

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