Update documentation with more than just tokens

[Mottie]

Duplicate check

• I've searched for any related issues and avoided creating a duplicate issue.

This update is for:

Content style guide

What is the name?

CSS Library docs

What is the nature of this update?

• How to build this component/pattern
• When to use this component/pattern
• When to use something else
• Usability guidance
• Accessibility considerations
• Content considerations
• Implementation
• Package information
• Addition to Forms Library documentation
• Update to existing Forms Library documentation

What problem does this solve?

I was trying to look up how to set a small font size:

Foundation documentation still exists? Or does the link and page just need to be renamed to CSS library?

In the typography section, only the token names are shown. For someone un-familiar with the design system (or someone not paying attention when they copy-pasted, like me), they would see a token of vads-font-size-sm and not realize that the corresponding class name to use is vads-u-font-size--sm; or, a CSS variable of --font-size-sm. It'd be awesome if this information was also included.

Additional Context

No response