Change to explanation or definition.

Change to explanation or definition. And testing Windows GUI interface for GitHub fork, clone, and merge requests.
I think it will look better if you leave that line alone and change this line (the bit inside the `<p>` tags). The line you've changed is a heading (`<h2>` is heading level 2), and having full sentences in a heading usually looks bad.

The actual text you added is fine, though.