How to add an image to a gist
Create a gist if you haven't already.
Clone your gist:
# make sure to replace `<hash>` with your gist's hash
git clone https://gist.github.com/<hash>.git # with https
git clone git@gist.github.com:<hash>.git # or with ssh
Add your image to your gist's repository:
git add your-image.jpg
Commit the image:
git commit -m "Add image"
Update gist:
git push origin master