Add system requirements to readme

README.md

@@ -18,6 +18,11 @@ number of ways depending on your needs. You can edit your wiki locally:
 Gollum follows the rules of [Semantic Versioning](http://semver.org/) and uses
 [TomDoc](http://tomdoc.org/) for inline documentation.
+## SYSTEM REQUIREMENTS
+- Python 2.5 or greater (for pygments.rb)
+- Ruby 1.8.7 or 1.9.3
+- Unix like operating system (OS X, Ubuntu, Debian, and more)
+- Will not work on Windows (because of grit)
 ## INSTALLATION