need Sketch 43+
Download Zip File, and double click on SketchToGit.sketchplugin. That's it
This plugin don't manage your git folder. You need to do this with CLI or GUI.
To use git with CLI
$ git init
$ git checkout -b newBranch
Make your change on sketch. Click on Unzip option or press Cmd + Shift + U.
Don't forget to generate .gitignore with "*.sketch"
Then
$ git add --all
$ git commit -m "[CHG] DESCRIBE YOUR CHANGE HERE"
You can do this with Git GUI like Git Kraken or Github Desktop.
Inspired by https://github.com/mathieudutour/git-sketch-plugin