Typo in 10.2 "Dynamically Sized Types"

I am reading the Rust reference. Looking at [section 10.2 "Dynamically sized types"](https://doc.rust-lang.org/stable/reference/dynamically-sized-types.html) I find:

> DSTs can be provided as type arguments when a bound of `?Sized`.

This sentence does not verb. I don't understand what it is trying to say, so I cannot make a PR. Should the words "is provided" be at the end?
