rephrase: struct -> type

Co-authored-by: Joshua Nelson <joshua@yottadb.com>

Author: janriemer

library/core/src/marker.rs

@@ -315,7 +315,7 @@ pub trait StructuralEq {
 /// the trait `Copy` may not be implemented for this type; field `points` does not implement `Copy`
 /// ```
 ///
-/// Shared references (`&T`) are also `Copy`, so a struct can be `Copy`, even when it holds
+/// Shared references (`&T`) are also `Copy`, so a type can be `Copy`, even when it holds
 /// shared references of types `T` that are *not* `Copy`. Consider the following struct,
 /// which can implement `Copy`, because it only holds a *shared reference* to our non-`Copy`
 /// type `PointList` from above: