Adding a screenshot in a github's

Today's work is about a ruby project hosted at github.comtodo-summarizer, a tool I use to compute weekly statistics on my development tree, and the task is to enhance project documentation.

The github-flavored markdown-based README is already quite explicit but it tends to show this tool only has a terminal output, but since todo-summarizer also offers a GTK-based GUI, I'd like to add some screenshots of the running application.

I quickly found this stackoverflow's answer and its relative URLs trick. In fact, as announced in this blog post, github supports relative links in markup files. So, if the screenshot is saved in a file called doc/screenshots/screenshot.png, you must add the following code to your file :

![GTK screenShot](doc/screenshots/screenshot.png) 

This way, it should work in forks, even if multiple branches contain different screenshots. You can see the final commit here.