Removes configuration flag example related to @redmine:plugins:assets@ (#40204, #39111).

git-svn-id: https://svn.redmine.org/redmine/trunk@22691 e93f8b46-1217-0410-a6f0-8f06a7374b81

config/configuration.yml.example

@@ -153,12 +153,6 @@ default:
   # * encrypt data using 'rake db:encrypt RAILS_ENV=production'
   database_cipher_key:
 
-  # Set this to false to disable plugins' assets mirroring on startup.
-  # You can use `rake redmine:plugins:assets` to manually mirror assets
-  # to public/plugin_assets when you install/upgrade a Redmine plugin.
-  #
-  #mirror_plugins_assets_on_startup: false
-
   # Your secret key for verifying cookie session data integrity. If you
   # change this key, all old sessions will become invalid! Make sure the
   # secret is at least 30 characters and all random, no regular words or