[SE-0258] Update implementation and pitch #3 links

Author: DougGregor

proposals/0258-property-wrappers.md

@@ -4,7 +4,7 @@
 * Authors: [Doug Gregor](https://github.com/DougGregor), [Joe Groff](https://github.com/jckarter)
 * Review Manager: [John McCall](https://github.com/rjmccall)
 * Status: **Returned for revision**
-* Implementation: Available as a "hidden" feature in [master snapshots](https://swift.org/download/#snapshots) with the attribute name `@_propertyDelegate` and using `delegateValue` in lieu of `wrapperValue`.
+* Implementation: Available in [master snapshots](https://swift.org/download/#snapshots).
 * Review: ([review #1](https://forums.swift.org/t/se-0258-property-delegates/23139)) ([revision announcement #1](https://forums.swift.org/t/returned-for-revision-se-0258-property-delegates/24080))
 * Previous versions: [Revision #1](https://github.com/apple/swift-evolution/commit/8c3499ec5bc22713b150e2234516af3cb8b16a0b)
 
@@ -19,6 +19,7 @@ This is an alternative approach to some of the problems intended to be addressed
 
 [Pitch #1](https://forums.swift.org/t/pitch-property-delegates/21895)<br/>
 [Pitch #2](https://forums.swift.org/t/pitch-2-property-delegates-by-custom-attributes/22855)<br/>
+[Pitch #3](https://forums.swift.org/t/pitch-3-property-wrappers-formerly-known-as-property-delegates/24961)<br/>
 
 ## Motivation