fix(info): Fix typo (rust-lang#635)

Co-authored-by: John Baber-Lucero <git@frundle.com>

info.toml

@@ -284,7 +284,7 @@ hint = """
 Rust has more than one type of struct. Three actually, all variants are used to package related data together.
 There are normal (or classic) structs. These are named collections of related data stored in fields.
 Tuple structs are basically just named tuples.
-Finally, Unit structs. These don't have and fields and are useful for generics.
+Finally, Unit structs. These don't have any fields and are useful for generics.
 
 In this exercise you need to complete and implement one of each kind.
 Read more about structs in The Book: https://doc.rust-lang.org/book/ch05-01-defining-structs.html"""