Extend product attributes probably referencing the wrong file

[funder7]

Hi,
I was reading the extend product atttributes guide, and there's something that doesn't look right:

In the code just after the migration, where the ProductDecorator is defined, I can see this path underneath:
File Location: app/models/railsapp_name/spree/product_serializer_decorator.rb (Does not exist by default)

Shouldn't this be named like: app/models/railsapp_name/spree/product_decorator.rb ?
Also I'd expect this:

::Spree::V2::Storefront::Product.prepend RailsappName::Spree::ProductDecorator if ::Spree::V2::Storefront::Product.included_modules.exclude?(RailsappName::Spree::ProductDecorator)

to be like:

::Spree::Product.prepend RailsappName::Spree::ProductDecorator if ::Spree::Product.included_modules.exclude?(RailsappName::Spree::ProductDecorator)

I'm opening an issue instead of doing a PR as I'm not really sure about it.

Cheers