Add Changelog for Az.DesktopVirtualization (Azure#26439)

* Add Changelog for Az.DesktopVirtualization

* Update ChangeLog.md

---------

Co-authored-by: NanxiangLiu <[email protected]>

Author: msJinLei

src/DesktopVirtualization/DesktopVirtualization/ChangeLog.md

@@ -18,6 +18,7 @@
         - Additional information about change #1
 -->
 ## Upcoming Release
+* Preannounced the breaking changes for Az.DesktopVirtualization 6.0.0
 
 ## Version 4.3.1
 * Introduced secrets detection feature to safeguard sensitive data.