fix: adding PR numbers to changelog.md

Author: Elfi0Kuhndorf

Packages/com.unity.multiplayer.samples.coop/CHANGELOG.md

@@ -3,15 +3,14 @@
 ## [Unreleased]
 
 ### Changed
-* Replaced Lobby and Relay standalone packages with the Multiplayer Services package v1.0.2
+* Replaced Lobby and Relay standalone packages with the Multiplayer Services package v1.0.2 (#892)
 * Removed UnityRelayUtilities
-* Upgrading Editor version dependency to 6000.0
-* Upgrading package dependencies:
+* Upgrading Editor version dependency to 6000.0 (#902)
+Upgrading package dependencies:
  *   Tutorial Framework upgraded to  v4.0.4
  *   Multiplayer Tools to v2.2.3
  *   Netcode for GameObjects to v2.2.0 
 
-
 ## [1.9.0] - 2024-04-18
 
 ### Changed