Add newly added PVTv2 model to all README files.

[robinverduijn]

What does this PR do?

Recent changes added the PVTv2 model but did not update all READMEs. This PR fixes the check_copies.py failures from CircleCI by adding PVTv2 to all README files.

• Also fixes a relative path for FastSpeech2Conformer model in README_ru.md

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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• Was this discussed/approved via a Github issue or the forum?
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• Did you make sure to update the documentation with your changes?
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• Did you write any new necessary tests?

Who can review?

Anyone in the community is free to review the PR once the tests have passed. Feel free to tag members/contributors who may be interested in your PR.

@amyeroberts @khipp @FoamoftheSea

[khipp]

LGTM!

PR #29647 and PR #29574 didn't have the updated utils/check_copies.py file yet. Running python utils/check_copies.py --fix_and_overwrite on the main branch now correctly applies the changes.

[amyeroberts]

Thanks!

[HuggingFaceDocBuilderDev]

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