Link to primitive instead of module

Author: denisvasilik

library/core/src/alloc/layout.rs

@@ -145,7 +145,7 @@ impl Layout {
     ///
     /// - If `T` is `Sized`, this function is always safe to call.
     /// - If the unsized tail of `T` is:
-    ///     - a [`crate::slice`], then the length of the slice tail must be an intialized
+    ///     - a [slice], then the length of the slice tail must be an intialized
     ///       integer, and the size of the *entire value*
     ///       (dynamic tail length + statically sized prefix) must fit in `isize`.
     ///     - a [trait object], then the vtable part of the pointer must point
@@ -158,6 +158,7 @@ impl Layout {
     ///       [`Layout::for_value`] on a reference to an extern type tail.
     ///     - otherwise, it is conservatively not allowed to call this function.
     ///
+    /// [slice]: ../../std/primitive.slice.html
     /// [trait object]: ../../book/ch17-02-trait-objects.html
     /// [extern type]: ../../unstable-book/language-features/extern-types.html
     #[unstable(feature = "layout_for_ptr", issue = "69835")]