guides: configuring: fixing explanation of :after_initialize hook

:after_initialize runs after config/initializers, not before.

Under 3.1, the document says

> `config.after_initialize` takes a block which will be run after Rails has finished initializing the application. That includes the initialization of the framework itself, engines, and all the application's initializers in config/initializers.

Under 6, the document says:

> `after_initialize`: Run directly after the initialization of the application, but before the application initializers are run.

This is wrong, as its name suggests, `after_initialize` is run _after_ the initializers in `config/initializers` have run. I also did a quick test with Rails 4.0.0:

    cd /tmp/
    rails new test_initialization_hooks

Hook into `:after_initialize`:

    # config/application.rb
    module TestInitializationHooks
      class Application < Rails::Application
        config.after_initialize do
          Rails.logger.info "This is the :after_initialize hook."
        end
      end
    end

Create an initializer on `config/initializers`:

    # config/initializers/test_initialization_hooks.rb
    Rails.logger.info 'This is config/initializers/test_initialization_hooks.rb'

Then, after testing to start the application in both development and production with `RAILS_ENV=development rails s` and `RAILS_ENV=production rails s`, the log files show:

    /tmp/test_initialization_hooks$ tail log/development.log 
    This is config/initializers/test_initialization_hooks.rb
    This is the :after_initialize hook.

And likewise:

    /tmp/test_initialization_hooks$ tail log/production.log 
    I, [2013-10-01T13:27:22.657053 #8578]  INFO -- : This is config/initializers/test_initialization_hooks.rb
    I, [2013-10-01T13:27:23.129267 #8578]  INFO -- : This is the :after_initialize hook.

The `:after_initialize` hooks runs after the initializers found in `config/initializers`, not before.