Update ChangeLog for VMSS Redeploy and PerformMaintenance.

Author: hyonholee

src/ResourceManager/Compute/ChangeLog.md

@@ -18,6 +18,8 @@
         - Additional information about change #1
 -->
 ## Current Release
+* VMSS Redeploy and PerformMaintenance feature
+    -  Add new switch parameter -Redeploy and -PerformMaintenance to `Set-AzureRmVmss` and `Set-AzureRmVmssVM`
 * Add DisableVMAgent switch parameter to `Set-AzureRmVMOperatingSystem` cmdlet
 * `New-AzureRmVm` and `New-AzureRmVmss` (simple parameter set) support a `Win10` image.
 * `Repair-AzureRmVmssServiceFabricUpdateDomain` cmdlet is added.