Here is the image file: https://gist.github.com/mbostock/5503544#file-thumbnail-png
I tried to drag-and-drop the image file in the edit mode of a gist. That didn\'t
uploading the image somewhere and using the HTML <img> tag works for me
Clone your gist:
git clone https://gist.github.com/<hash>.git
Add your image to your gist's repository:
git add my-image.jpg
Commit the image:
git commit -m "adding my image to my gist"
Update gist by pushing you modifications:
git push origin master