fix(structs1): Adjust wording (#573)

Co-authored-by: fmoko <mokou@posteo.de>

info.toml

@@ -225,12 +225,13 @@ name = "structs1"
 path = "exercises/structs/structs1.rs"
 mode = "test"
 hint = """
-Rust has more than one type of struct. Both variants are used to package related data together.
-On the one hand, there are normal, or classic, structs. These are named collections of related data stored in fields.
-The other variant is tuple structs. Basically just named tuples.
-In this exercise you need to implement one of each kind.
+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.
 
-Read more about structs in The Book: https://doc.rust-lang.org/stable/book/ch05-00-structs.html"""
+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"""
 
 [[exercises]]
 name = "structs2"