Updated change log for RS Backup module (#2579)

Author: Samuel Anudeep

ChangeLog.md

@@ -65,6 +65,11 @@
 * Azure API Management
   * Fixed Azure Api Management Deployment cmdlets for AzureChinaCloud.
   * Removed cmdlet Set-AzureRmApiManagementTenantGitAccess as Git Access is enabled by Default.
+* Azure Recovery Services Backup
+  * Added support for the Azure SQL workload
+  * Added support for backing up and restoring encrypted Azure VMs
+  * Backup-AzureRmRecoveryServicesBackupItem - Added optional retention time feature for recovery points
+  * Minor filter-related bug fixes in Get-AzureRmRecoveryServicesBackupContainer and Get-AzureRmRecoveryServicesBackupItem cmdlets
 
 ##2016.06.23 version 1.5.1
 * Azure Resource Manager