[Docs] Component review and design improvements

[aweell]

Component reviews

• [Upload] Component specs #190
• [Slider] Component specs #224
• [Switch] Component specs #225
• [Dialog] Documentation review #443
• [Checkbox] Color specs update #477
• [Checkbox] Component spacing and sizing #478
• [Box] Documentation review #497
• [Button] Variant tokens update #499
• [Radio] Documentation review #530
• [Tag] Documentation review #542
• [Slider] Add label and helper text #619

Fixes

• [Footer] Documentation fixes #322
• [Chip] Documentation fixes #323
• [Alert] Fixes on component specs #437
• [Button] Update :focus color token #460
• [Accordion] Remove heading anchors #474
• [Button] Component updates #547
• [Slider] Documentation fixes #572
• [Accordion] Documentation fixes #588
• [Header] Add contentColor token #645
• [Table] Change on the <td> font-size #646
• [Release] Fixes for v4.0.0 #656

Design improvements

• [Accordion] Focus state #583
• [Button] Variants hierarchy #607

[aweell]

Closed via #608, #620, #584

[aweell]

[Update] 4.0.0

• Added [Table] Change on the <td> font-size #646
• Added [Header] Add contentColor token #645

[aweell]

Closed via #647 and #652