Docs for torchcompile and functorch (#101881)
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### <samp>🤖 Generated by Copilot at b5f48b6</samp>
> _`torch.compile` docs_
> _Add a new section for `func`_
> _Winter of features_
Thanks @zou3519
Pull Request resolved: https://github.com/pytorch/pytorch/pull/101881
Approved by: https://github.com/eellison, https://github.com/zou3519
