docs: fix typos and a broken link in PR template

[Oreoxmt]

📝 Summary

Fix typos in the following documents:

• docs/guides/ai_completion.md
• docs/recipes.md
• marimo/_plugins/ui/_impl/batch.py

Fix a broken link [contributor guidelines](../CONTRIBUTING.md) in PR template

🔍 Description of Changes

📋 Checklist

• [x] I have read the contributor guidelines.
• [ ] For large changes, or changes that affect the public API: this change was discussed or approved through an issue, on Discord, or the community discussions (Please provide a link if applicable).
• [ ] I have added tests for the changes made.
• [ ] I have run the code and verified that it works as expected.

📜 Reviewers

@akshayka OR @mscolnick

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Name	Status	Preview	Comments	Updated (UTC)
marimo-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 3, 2024 7:55am
marimo-storybook	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 3, 2024 7:55am

[github-actions[bot]]

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

[Oreoxmt]

I have read the CLA Document and I hereby sign the CLA

[Oreoxmt]

recheck

[Oreoxmt]

@mscolnick Could you please help review this PR? Thanks