message: add Link component prop docs
diff: Link components get `COMMON` system props. Read our [System Props](/system-props) doc page for a full list of available props.
  +## Component props
  +
  +| Prop name | Type | Description |
  +| :- | :- | :- |
  +| href | String | URL to be used for the Link |
  +| muted | Boolean | Applies a gray text color to the Link |
  +| nounderline | Boolean | Removes underline from the Link |
  +| scheme | String | Can be `gray` or `gray-dark`, sets the text color accordingly. |
  +
  export const meta = {displayName: 'Link'}
  