HACK: Add dummy plugin folder

On some installations, there may be a leftover symlink which uses the
old plugin name:

  public/plugins/discourse-internet-explorer ->
  -> plugins/discourse-internet-explorer/public

.gitignore

@@ -54,6 +54,7 @@ bootsnap-compile-cache/
 !/plugins/discourse-narrative-bot
 !/plugins/discourse-presence
 !/plugins/discourse-local-dates
+!/plugins/discourse-internet-explorer
 !/plugins/discourse-unsupported-browser
 /plugins/*/auto_generated/