docs: update static to isr

[nateemerson]

🔗 Linked issue

#20963

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Update key in descriptions list of "Rendering Modes" documentation page to use isr and match code snippet.

Resolves #20963

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[nuxt-studio]

✅ Live Preview ready!

Name	Edit	Preview	Latest Commit
Nuxt Docs	Edit on Studio ↗︎	View Live Preview	50d7bb1

[nateemerson]

@danielroe's suggestions incorporated!

[danielroe]

Thank you ❤️

[flexchar]

1. Is it correct to assume that isr/swr provides that same behaviour as static?

I'm having trouble understanding the variety of options. The re-rendering sounds very appealing but the reason for going for Static Site Generation mode is the highest performance. Which seems to be lost when using swr/isr.

2. Is static mode deprecated? I'm trying to understand your PR logic. It's like documentation for me.

@nateemerson