Add back in `config_for` example

[ci skip]

1 files changed, 28 insertions, 0 deletions

diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index c013973d02..47144db0c2 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -1234,6 +1234,34 @@ These configuration points are then available through the configuration object:
   Rails.configuration.x.super_debugger.not_set      # => nil
   ```
 
+
+You can also use `Rails::Application.config_for` to load whole configuration files:
+
+  ```ruby
+  # config/payment.yml:
+  production:
+    environment: production
+    merchant_id: production_merchant_id
+    public_key:  production_public_key
+    private_key: production_private_key
+  development:
+    environment: sandbox
+    merchant_id: development_merchant_id
+    public_key:  development_public_key
+    private_key: development_private_key
+
+  # config/application.rb
+  module MyApp
+    class Application < Rails::Application
+      config.payment = config_for(:payment)
+    end
+  end
+  ```
+
+  ```ruby
+  Rails.configuration.payment['merchant_id'] # => production_merchant_id or development_merchant_id
+  ```
+
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