Fix link to CONTRIBUTING on README

Author: ybiquitous

README.rdoc

@@ -123,7 +123,7 @@ Please follow the theme's README for usage instructions.
 
 == Bugs
 
-See CONTRIBUTING@Bugs for information on filing a bug report.  It's OK to file
+See CONTRIBUTING.rdoc for information on filing a bug report.  It's OK to file
 a bug report for anything you're having a problem with.  If you can't figure
 out how to make RDoc produce the output you like that is probably a
 documentation bug.