message: chore(readme): indicate Angular version support
diff: [https://willsoto.github.io/ng-chartist/docs/](https://willsoto.github.io/ng-chartist/docs/)
  +## Angular Version Support
  +
  +| Angular | ng-chartist |
  +| ------- | ----------- |
  +| 12x | 5x |
  +| <=11x | 4x |
  +
  ## Table of contents
  - [About](#about)
  