rails/rails — pull request #9816 by sebasoga (2013-03-19 22:38:53+00:00)
Title: Fix guides error on error class name

The error that's raised in case the required key is missing it's actually `ActionController::ParameterMissing` not `ActionController::MissingParameter`. It's important to fix so that people reading the guides knows what error to rescue from when needed.