jsDelivr CDN for CSUR

1. Upload assets.

2. Creat a new release.

3. Get the file link.

https://cdn.jsdelivr.net/gh/<USERNAME>/<REPO>@<VERSION>/<PATH>
  
or ignore the version number, referencing the latest version of the file.
  
https://cdn.jsdelivr.net/gh/<USERNAME>/<REPO>/<PATH>

e.g. https://cdn.jsdelivr.net/gh/citiesskylines-csur/CDN/m1-1.png