Feat: Add ability to hide props from the docs

[pgmanutd]

Right now there is no official way to hide props from the docs. Probably we can use something like @internal or @private to hide them.

export interface Props {
  /** Some description */
  id?: string;
  /**
   * @internal
   * Some description
   */
  privateId?: string
}

[jenniesyip]

Reminds me of: http://sassdoc.com/annotations/#access