Add PR number to CHANGELOG entries

Author: simon-lemay-unity

com.unity.netcode.gameobjects/CHANGELOG.md

@@ -10,11 +10,11 @@ Additional documentation and release notes are available at [Multiplayer Documen
 
 ### Added
 
-- Added a new variant of `UnityTransport.GetDefaultPipelineConfigurations` that takes a reference to the created `NetworkDriver`. This will register all pipeline stages that `UnityTransport` requires, removing the need to manually register them in your own custom driver constructor.
+- Added a new variant of `UnityTransport.GetDefaultPipelineConfigurations` that takes a reference to the created `NetworkDriver`. This will register all pipeline stages that `UnityTransport` requires, removing the need to manually register them in your own custom driver constructor. (#3980)
 
 ### Changed
 
-- `NetworkMetricsPipelineStage` is now defined even when the multiplayer tools package is not installed, removing the need to guard its registration behind a version define when using a custom driver in `UnityTransport`.
+- `NetworkMetricsPipelineStage` is now defined even when the multiplayer tools package is not installed, removing the need to guard its registration behind a version define when using a custom driver in `UnityTransport`. (#3980)
 
 ### Deprecated