What does " your own Spec in practise" mean?

I cannot for the life of me figure out how to use `quoted_string::to_content` in 0.6. The docs at https://docs.rs/quoted-string/0.6.1/quoted_string/fn.to_content.html use a "TestSpec" marker type thing and then say "use your own Spec in practise", but it doesn't seem obvious how to construct my own Spec and what decisions I'd want to choose in a particular Spec to make it "my own".