Rollup merge of rust-lang#76303 - jyn514:vec-assert-doc, r=Dylan-DPC

Link to `#capacity-and-reallocation` when using with_capacity

Follow up to rust-lang#76058 (comment).
r? @pickfire

Author: Dylan-DPC

library/alloc/src/vec.rs

@@ -120,6 +120,9 @@ use crate::raw_vec::RawVec;
 /// assert_eq!(vec, [0, 0, 0, 0, 0]);
 /// ```
 ///
+/// For more information, see
+/// [Capacity and Reallocation](#capacity-and-reallocation).
+///
 /// Use a `Vec<T>` as an efficient stack:
 ///
 /// ```