Fix broken link

docs/_layouts/default.html

@@ -28,7 +28,7 @@ <h1 style="display: inline"> NSubstitute </h1> <br />
 
   <div id="footer">
   NSubstitute is open source software, licensed under the <a href="http://www.opensource.org/licenses/bsd-license.php">BSD License</a>.<br />
-The NSubstitute project is possible <a href="http://github.com/nsubstitute/NSubstitute/blob/master/acknowledgements.markdown">thanks to a number of other software projects</a>. We acknowledge their awesomeness.<br />
+The NSubstitute project is possible <a href="https://github.com/nsubstitute/NSubstitute/blob/master/acknowledgements.md">thanks to a number of other software projects</a>. We acknowledge their awesomeness.<br />
 NSubstitute CI builds are run using <a href="http://www.jetbrains.com/teamcity/">TeamCity</a> kindly <a href="http://codebetter.com/codebetter-ci/">hosted by Codebetter</a>.<br />
   NSubstitute logo donated by <a href="http://troyhunt.com">Troy Hunt</a>.
   </div>