Add link to the review thread (#2652)

Author: DougGregor

proposals/0456-stdlib-span-properties.md

@@ -6,7 +6,7 @@
 * Status: **Active Review (January 15...28, 2024)
 * Roadmap: [BufferView Roadmap](https://forums.swift.org/t/66211)
 * Implementation: [PR #78561](https://github.com/swiftlang/swift/pull/78561)
-* Review: [pitch](https://forums.swift.org/t/76138)
+* Review: [Review](https://forums.swift.org/t/se-0456-add-span-providing-properties-to-standard-library-types/77233), [Pitch](https://forums.swift.org/t/76138)
 
 [SE-0446]: https://github.com/swiftlang/swift-evolution/blob/main/proposals/0446-non-escapable.md
 [SE-0447]: https://github.com/swiftlang/swift-evolution/blob/main/proposals/0447-span-access-shared-contiguous-storage.md