[ci skip] Add missing setting locale code snippet.

This is for 3 Internationalizing your Application of i18n.md.

Missing the code as mentioned in 2.3, setting locale.

Without this, the example to add config/locales/pirate.yml will not work.

1 files changed, 11 insertions, 0 deletions

diff --git a/guides/source/i18n.md b/guides/source/i18n.md
index c191db1df9..e3ca129189 100644
--- a/guides/source/i18n.md
+++ b/guides/source/i18n.md
@@ -316,6 +316,17 @@ end
 ```
 
 ```ruby
+# app/controllers/application_controller.rb
+class ApplicationController < ActionController::Base
+  before_action :set_locale
+
+  def set_locale
+    I18n.locale = params[:locale] || I18n.default_locale
+  end
+end
+```
+
+```ruby
 # app/controllers/home_controller.rb
 class HomeController < ApplicationController
   def index