Very cool - I've run into the exact problem you described many times in the past and actually considered building something very similar to this.

As a side note, it looks like <img>'s aren't working - try adding something like this:

  <img src="https://www.google.ca/images/branding/googlelogo/1x/googlelogo_color_272x92dp.png" />

Making images format correctly in GitHub READMEs has always been a bit of a pain point for me, so this would be a nice feature to have.