mention that this repo is based on hydeslides

Author: afeld

README.md

@@ -24,7 +24,7 @@ The educational content exists in two top level directories:
 
 ## File Format
 
-The majority of the site materials are written in [Markdown](http://whatismarkdown.com), a [lightweight markup language](http://en.wikipedia.org/wiki/Lightweight_markup_language) supported in the GitHub web application user interface. There is a syntax guide to the original [Markdown format](http://daringfireball.net/projects/markdown/syntax) and also [GitHub Flavored Markdown](http://github.github.com/github-flavored-markdown/).
+The majority of the site materials are written in [Markdown](http://whatismarkdown.com), a [lightweight markup language](http://en.wikipedia.org/wiki/Lightweight_markup_language) supported in the GitHub web application user interface. There is a syntax guide to the original [Markdown format](http://daringfireball.net/projects/markdown/syntax) and also [GitHub Flavored Markdown](http://github.github.com/github-flavored-markdown/).  These repository is based on [Hydeslides](https://github.com/jordanmccullough/HydeSlides), so see that repository for more information on the structure.
 
 ## Build