Add the creation of an RG

It's not well explained that the RG already exists,therefore
adding one so we dont break the creation flow.

Author: naioja

includes/virtual-machines-disks-encryption-create-key-vault-cli.md

@@ -30,6 +30,8 @@ diskName=yourDiskName
 
 az account set --subscription $subscriptionId
 
+az group create --resource-group $rgName --location $location
+
 az keyvault create -n $keyVaultName \
 -g $rgName \
 -l $location \