Add git tags

[sajochiu]

Hi @magnumjs,
We are cdnjs team, we are going to host this library.
The git auto-updater in cdnjs relies on git tags so that so that it can recognize the correct version and automatically update the repo.
Could you please add git tags for the repo? Thank you.
@x09326

[magnumjs]

Hi, I created a release with the latest version:

https://github.com/magnumjs/mag.js/releases