Updated changelog for imgui sync

Author: azonenberg

release-notes/CHANGELOG.md

@@ -12,3 +12,7 @@ This is a running list of significant bug fixes and new features since the last
 * Crash with vk::OutOfHostMemoryError when application is minimized on a Windows system with an Intel ARC GPU (https://github.com/ngscopeclient/scopehal-apps/issues/893)
 * Incorrect loading of CSV files with Windows line endings (https://github.com/ngscopeclient/scopehal/issues/1002)
 * Incorrect buffer size calculation in DeEmbedFilter unit test causing intermittent crashes of the test case in CI (no issue ticket)
+
+## Other changes since v0.1
+
+* Updated to latest upstream imgui (1.92.4 WIP)