Allow 'readme.md' to be read as readme file in diffusion

Summary: In the title!

Test Plan: View a readme file

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5914

src/applications/diffusion/conduit/ConduitAPI_diffusion_browsequery_Method.php

@@ -49,7 +49,7 @@ final class ConduitAPI_diffusion_browsequery_Method
 
       $path = $result_path->getPath();
 
-      if (preg_match('/^readme(|\.txt|\.remarkup|\.rainbow)$/i', $path)) {
+      if (preg_match('/^readme(|\.txt|\.remarkup|\.rainbow|\.md)$/i', $path)) {
         $readme = $result_path;
         break;
       }