[release] extension/CHANGELOG.md: add v0.40.2 entry

For golang/vscode-go#3142

Change-Id: I71ef7ed943472f4e5f9b979c9f077c3f959eaaa7
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/556859
Commit-Queue: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: kokoro <noreply+kokoro@google.com>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c0a31c7..ecae037 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+## v0.40.2 - 22 Jan, 2023
+
+This is a point release to update the upcoming developer survey information
+([the commit history](https://github.com/golang/vscode-go/compare/v0.40.1...v0.40.2)).
+
 ## v0.40.1 - 21 Dec, 2023
 
 This is a point release to fix minor bugs. A comprehensive list of bug fixes and