remove PR text from class, add link to slides.

Author: wslack

README.md

@@ -10,9 +10,4 @@ This was previously a repo for the microsite for [18F's Hour of Code](http://www
 
 ## Test Pull Requests
 
-If you are visiting because of the [GitHub for Beginners webinar](https://www.youtube.com/watch?v=uNa9GOtM6NE), please feel free to make Pull Requests below this text!
-
-Testing out a pull request.
-
-This is my edit. This is very helpful because I have always been confused of what a fork is vs. a straight up change when I have access to change. 
-
+If you are visiting because of the [GitHub for Beginners webinar](https://www.youtube.com/watch?v=uNa9GOtM6NE) ([slides](https://pages.18f.gov/slides/github-basics/#/)), please feel free to make pull requests below this text!