[changela] 新增 Youtube 與 Unreleased section

// Types of changes
export enum SectionTypes {
  Added = 'Added' ,      // for new features.
  Changed = 'Changed',    // for changes in existing functionality.
  Deprecated = 'Deprecated', // for soon-to-be removed features.
  Removed = 'Removed',    // for now removed features.
  Fixed = 'Fixed',      // for any bug fixes., SemVer's PATCH
  BreakingChanges = 'Breaking Changes', // for changes incompatibility with previous version.
  Unreleased = 'Unreleased',  // what changes they might expect in upcoming releases
                      // At release time, you can move the Unreleased section changes into a new release version section.
  Security = 'Security',    // in case of vulnerabilities.
  Video = 'Video',    // video
  Overview = 'Overview',    // Overview
}