Update Changelog.md

Author: msJinLei

src/Accounts/Accounts/ChangeLog.md

@@ -21,6 +21,7 @@
 ## Upcoming Release
 * Enabled caching tokens when logging in with a service principal. This could reduce network traffic and improve performance.
 * Upgraded target framework of Microsoft.Identity.Client to net461 [#20189]
+* Stored `ServicePrincipalSecret` and `CertificatePassword` into `AzKeyStore`.
 
 ## Version 2.10.3
 * Updated `Get-AzSubscription` to retrieve subscription by Id rather than listed all the subscriptions from server if subscription Id is provided. [#19115]