Update PT Cheat page to stop referencing torchscript

[janeyx99]

Description

Updates the pt cheat page to

• no longer mention jit/torchscript
• mention zero_grad for optim
• update the list of optims

Checklist

• The issue that is being fixed is referred in the description (see above "Fixes #ISSUE_NUMBER")
• Only one issue is addressed in this pull request
• Labels from the issue that this PR is fixing are added to this pull request
• No unnecessary issues are included into this pull request.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/tutorials/3139

• 📄 Preview Python docs built from this PR

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✅ No Failures

As of commit 63025f7 with merge base 4e9296e ():
💚 Looks good so far! There are no failures yet. 💚

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