Fix theme explanation

Author: zackbloom

README.md

@@ -48,8 +48,8 @@ Themes
 ------
 
 Pace includes a bunch of [themes](http://github.hubspot.com/pace/docs/themes/)
-to get you started.  Specify the theme of your choice as an option, and
-include the appropriate css file.
+to get you started.  Just include the appropriate css file.  Send us a PR with
+any interesting themes you create.
 
 Collectors
 ----------