Explain `Gitlab::Middleware::Static`.

config/initializers/static_files.rb

 begin
   app = Rails.application
+  # The `ActionDispatch::Static` middleware intercepts requests for static files 
+  # by checking if they exist in the `/public` directory. 
+  # We're replacing it with our `Gitlab::Middleware::Static` that does the same,
+  # except ignoring `/uploads`, letting those go through to the GitLab Rails app.
+
   app.config.middleware.swap(
     ActionDispatch::Static, 
     Gitlab::Middleware::Static,