[Docs] Document `Spinner` component

[carwack]

Document the CSpinner component under content/4.components.
Add needed examples under content/examples/{componentName}/{exampleName}.vue.

See: React Docs Github
See: Component in Chakra UI Vue Next Repo

🚨 Keep in mind

• Use PascalCase for components (in examples and code bocks)
• Use the Showcase component
  ex:

::showcase
:::colors-code
::