README updated

Other Debian based distros add in Ubuntu installation line

README.md

@@ -95,7 +95,7 @@ to install GhostScript. On Mac OS X, you can also install that using Homebrew:
 
     brew install gs
     
-If you're on Ubuntu, you'll want to run the following with apt-get:
+If you're on Ubuntu (or any Debian base Linux distribution), you'll want to run the following with apt-get:
 
     sudo apt-get install imagemagick -y