Update changelog.md of Az.accounts

Author: BethanyZhou

src/Accounts/Accounts/ChangeLog.md

@@ -18,6 +18,7 @@
         - Additional information about change #1
 -->
 ## Upcoming Release
+* Formatted the breaking change messages
 * Loaded all public cloud environments when discovery endpoint doesn't return default AzureCloud or other public environments [#12633]
 * Exposed SubscriptionPolicies in `Get-AzSubscription` [#12551]