[REF-3420] Add Docs for custom radix colorsheet

[dentroai]

trafficstars

Legendmor wrote 2 months ago that "We need to document this in the styling section" regarding how to use custom radix stylesheets.

As I can't find it in the docs yet, I will just paste the discord thread in question:

https://discord.com/channels/1029853095527727165/1240787272908144700/1240787677050175509

_REF-3420

[dentroai]

you can also add in the docs that this works both with the accent color and the gray color, so it's possible to load in a custom radix stylesheet for both

[dentroai]

This answer by Carlos should also definitely be added to these docs https://discord.com/channels/1029853095527727165/1267555647562584107/1267586312806993970

[LineIndent]

PR: https://github.com/reflex-dev/reflex-web/pull/1257