From the official Autodesk page:
Create or open a document with the styles you want to copy to the style library.
From the official For Dummies page:
Create a new document or open a document with styles that you can recycle. (Without the in front of styles.)
It seems Dummies version is an error, isn't it?
Another option is that both versions are correct, with a subtle difference in the assumed meaning. But I really don't see any difference in the context of these examples, and therefore one of them should be wrong (to my opinion).