Fix broken link to example _config.yml file (mmistakes#1069)

docs/_docs/05-configuration.md

@@ -505,7 +505,7 @@ defaults:
       layout: single
 ```
 
-And of course any default value can be overridden by settings in a post, page, or collection file. All you need to do is specify the settings in the YAML Front Matter. For more examples be sure to check out the demo site's [`_config.yml`](https://github.com/{{ site.repository }}/gh-pages/_config.yml).
+And of course any default value can be overridden by settings in a post, page, or collection file. All you need to do is specify the settings in the YAML Front Matter. For more examples be sure to check out the demo site's [`_config.yml`](https://github.com/mmistakes/minimal-mistakes/blob/master/_config.yml).
 
 ## Outputting