extension/src: add package outline to changelog

Change-Id: I2801745b8068d95621bb123b7793d334a460a71c
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/648216
Reviewed-by: Hongxiang Jiang <[email protected]>
kokoro-CI: kokoro <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: madelinekalil

CHANGELOG.md

@@ -9,6 +9,12 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/).
 
 * The testing framework is migrated from `Kokoro` to `LUCI`. The presubmit tests will be triggered against multiple go versions.
 
+### Changes
+
+#### Package Outline View
+
+* Added new "Package Outline" explorer view that displays all the symbols in the currently open file's package.
+
 ## v0.45.0 (prerelease)
 
 Date: 2024-12-16