docs: `RenderOnce` and `dangerouslySetInnerHTML`

[zanettin]

fixes #1675 fixes #2403

What is it?

• [ ] Feature / enhancement
• [ ] Bug
• [x] Docs / tests

Checklist:

• [x] My code follows the developer guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have made corresponding changes to the documentation
• [ ] Added new tests to cover the fix / functionality

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[zanettin]

@shairez @manucorporat: didn't find a good example to demonstrate <RenderOnce> on the docs. do you have smth i could use here?

[zanettin]

thanks @literalpie 🙏

[shairez]

awesome job @zanettin ! merging!