docs: add percentage value support for gap and transform properties

[supunyasanthaofficial]

Fixes #4265

Summary

Updates the documentation for percentage values supported by Yoga 3.1 on the New Architecture.

• Removed the outdated pixel-only note for gap, columnGap, and rowGap.
• Documented percentage string support such as '10%' for these properties.
• Updated the type definitions to include string.
• Added percentage support examples for translateX and translateY.
• Clarified how percentage values are calculated for transforms.
• Updated the Flexbox documentation to mention percentage values for gap properties.

Test Plan

• Ran Prettier on the modified files.
• Ran ESLint on the modified documentation files.
• Verified the Docusaurus site builds successfully.

[Simek]

Hey @supunyasanthaofficial, can you backport the changes to the versioned doc files, since as mentioned in the issue, those changes landed in 0.75?

[supunyasanthaofficial]

Done! I've backported the changes across all versioned doc versions (0.77 – 0.87).

[Simek]

Thanks for the quick update, LGTM! 🚀