Add Documentation For frui.css

[cblanquera]

Describe the feature you'd like to request

From a project. We need to understand the FRUI stylesheet, in order to customize it.

Describe the solution you'd like

A new webpage describing how to customize all the components in FRUI in general (ie. a style guide).

Describe alternatives you've considered

Reading the code, but everyone looking to customize FRUI would also need to sift through the code and figure it out. Save us some time please!

[cblanquera]

👋 @cblanquera
Thank you for raising an issue! Please make sure you have given as much context as possible. Screenshots are appreciated!

[cblanquera]

This issue is stale because it has been open for 30 days with no activity.

[cblanquera]

This issue was closed because it has been inactive for 14 days since being marked as stale.