Update docs to document --no-watch

[ricokahler]

This is a documentation pull recommended by @mrmckeb in #6285 (comment) to let people know that --no-watch now exists.

I basically just searched for watch and test and I tried to add a bit of info here and there. I'm not a doc writer or anything and I might've missed a few spots but here ya go!

---

Feel free to directly edit this branch or similar. I see this PR as more of a reminder that this should be done.

[mrmckeb]

Hey @ricokahler, thanks for this. A few changes here, and we'll be good to merge.

I want to keep this change as small as possible, as we do want users to be running in watch mode most of the time, and don't want them to confuse this new flag with CI=true.

[ricokahler]

@mrmckeb I've finished the changes you've requested. I also changed the configuration for "Debugging Tests in Visual Studio Code" to add this flag because that's why I wanted it in the first place lol.

Let me know if I missed anything and thanks again for the opportunity!

[mrmckeb]

Thanks @ricokahler, this looks good.

I think it would be cool if you could also create a PR to add the same here: https://jestjs.io/docs/en/troubleshooting (as they reference the same VSCode config for CRA).

If you can't, let me know and I'll do it :)

If the Jest team do come up with a way to make test debugging work better with watch mode, we can remove that from the docs.

[ricokahler]

If you can't, let me know and I'll do it :)

@mrmckeb I'm a bit tied up at the moment so it'd be better if you could. Thanks again for the opportunity to contribute

[mrmckeb]

No problem, thanks for your time. We'll add this after the next release.