docs: Add more new docs content

[reidbarber]

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices

📝 Test Instructions:

🧢 Your Project:

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the documentation
• View the S2 docs

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the documentation
• View the S2 docs

[rspbot]

## API Changes

@react-spectrum/s2

/@react-spectrum/s2:UserCard

 UserCard {
   UNSAFE_className?: UnsafeClassName
   UNSAFE_style?: CSSProperties
   children: ReactNode | (CardRenderProps) => ReactNode
-  density?: 'compact' | 'regular' | 'spacious' = 'regular'
   download?: boolean | string
   href?: Href
   hrefLang?: string
   id?: Key
   isDisabled?: boolean
   onAction?: () => void
   onPress?: (PressEvent) => void
   onPressChange?: (boolean) => void
   onPressEnd?: (PressEvent) => void
   onPressStart?: (PressEvent) => void
   onPressUp?: (PressEvent) => void
   ping?: string
   referrerPolicy?: HTMLAttributeReferrerPolicy
   rel?: string
   routerOptions?: RouterOptions
   size?: 'XS' | 'S' | 'M' | 'L' | 'XL' = 'M'
   styles?: StylesProp
   target?: HTMLAttributeAnchorTarget
   textValue?: string
   value?: T
-  variant?: 'primary' | 'secondary' | 'tertiary' | 'quiet' = 'primary'
+  variant?: 'primary' | 'secondary' | 'tertiary'
 }

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