Fixing links to contribution and CoC

Author: gvwilson

_includes/contributing.md

@@ -4,6 +4,6 @@ Please <a href="mailto:{{site.email}}">email us</a>,
 <a href="{{site.repo}}issues">file an issue</a> in <a href="{{site.repo}}">our GitHub repository</a>,
 or <a href="{{site.repo}}pulls">submit a pull request</a>.
 Everyone whose work is incorporated will be acknowledged.
-Please see <a href="{{'/en/contributing/'|relative_url}}">the contributors's guide</a> for more information,
+Please see <a href="{{'/en/contributing.html'|relative_url}}">the contributors's guide</a> for more information,
 and please note that all contributors are required to abide by
-our <a href="{{'/en/conduct/'|relative_url}}">Code of Conduct</a>.
+our <a href="{{'/en/conduct.html'|relative_url}}">Code of Conduct</a>.