Allow viewing documents as both .txt and .md

Author: carlbennett

src/controllers/Document/View.php

@@ -52,7 +52,7 @@ public function run(Router &$router) {
       case "htm": case "html": case "":
         $view = new DocumentViewHtmlView();
       break;
-      case "txt":
+      case "md": case "txt":
         $view = new DocumentViewPlainView();
       break;
       default: