Rails::Application#secrets should be documented.

railties/lib/rails/application.rb

@@ -368,7 +368,21 @@ def config=(configuration) #:nodoc:
       @config = configuration
     end
 
-    def secrets #:nodoc:
+    # Returns secrets added to config/secrets.yml.
+    #
+    # Example:
+    #
+    #     development:
+    #       secret_key_base: 836fa3665997a860728bcb9e9a1e704d427cfc920e79d847d79c8a9a907b9e965defa4154b2b86bdec6930adbe33f21364523a6f6ce363865724549fdfc08553
+    #     test:
+    #       secret_key_base: 5a37811464e7d378488b0f073e2193b093682e4e21f5d6f3ae0a4e1781e61a351fdc878a843424e81c73fb484a40d23f92c8dafac4870e74ede6e5e174423010
+    #     production:
+    #       secret_key_base: <%= ENV["SECRET_KEY_BASE"] %>
+    #       namespace: my_app_production
+    #
+    # +Rails.application.secrets.namespace+ returns +my_app_production+ in the
+    # production environment.
+    def secrets
       @secrets ||= begin
         secrets = ActiveSupport::OrderedOptions.new
         yaml = config.paths["config/secrets"].first