docs: add remaining docs for classes in app/logical.

app/logical/routes.rb

@@ -1,6 +1,11 @@
 # Allow Rails URL helpers to be used outside of views.
-# Example: Routes.posts_path(tags: "touhou") => /posts?tags=touhou
-
+#
+# @example
+#   Routes.posts_path(tags: "touhou")
+#   => "/posts?tags=touhou"
+#
+# @see config/routes.rb
+# @see https://guides.rubyonrails.org/routing.html
 class Routes
   include Singleton
   include Rails.application.routes.url_helpers