Added requirement for subs to be registered in the ManagedService pro…

…vider namespace

README.md

@@ -62,6 +62,8 @@ If you're unsure about what/how to use this module, please fill the [questionnai
 - For scanning, an App (with its Service Principal) is required to be created in the ActiveDirectory, to enable
   ContainerRegistry Task to run the image scanning This requires subscription-level `Security Administrator` role.
 
+- The subscription(s) to onboard must be registered to the 'Microsoft.ManagedService' services provider namespace. More info on [how to enroll your subscription here](https://learn.microsoft.com/en-us/azure/azure-resource-manager/management/resource-providers-and-types#:~:text=Azure%20portal-,Register%20resource%20provider,-To%20see%20all).
+
 Note: Beware that previous roles in AD are found in two different levels; Organizational level (user AD **Assigned
 Roles**), and Subscription level (user AD **Azure role assignments**). This role assignments take some time to
 consolidate.