Add missing static resource.

Author: gspencergoog

lib/src/html/resources.g.dart

@@ -10,6 +10,7 @@ const List<String> resource_names = const [
   'package:dartdoc/resources/favicon.png',
   'package:dartdoc/resources/github.css',
   'package:dartdoc/resources/highlight.pack.js',
+  'package:dartdoc/resources/play_button.svg',
   'package:dartdoc/resources/readme.md',
   'package:dartdoc/resources/script.js',
   'package:dartdoc/resources/sdk_footer_text.html',