add code comments and bring back the singleton

Using singleton avoids initialisation of the Settings class (which is mostly global)

app/views/includes/_footer.html.erb

@@ -11,7 +11,7 @@
             <%= link_to t('.home'), root_path %>
           </li>
           <li class="mt-3 mt-sm-2">
-            <%= link_to t('.contact'), "mailto:#{Settings.contact_email}" %>
+            <%= link_to t('.contact'), "mailto:#{Settings.instance.contact_email}" %>
           </li>
           <li class="mt-3 mt-sm-2">
             <%= link_to t('.stories'), stories_path %>

config/initializers/settings.rb

@@ -1,7 +1,17 @@
+# The Settings class is a singleton class which holds all configuration
+# which is accessed throughout the application outside of `config` files.
+# These settings mostly include environemt variables and other global settings.
+#
+# Similar pattern and inspiration from:
+# https://garrettdimon.com/journal/posts/unified-configuration-in-rails
+#
+# Usage: Settings.instance.contact_email
+#
+
 class Settings
-  class << self
-    def contact_email
-      ENV["DOMAIN_EMAIL_ADDRESS"]
-    end
+  include Singleton
+
+  def contact_email
+    ENV["DOMAIN_EMAIL_ADDRESS"]
   end
 end