Microsoft.ServiceFabric version 2021-05-01 is missing

It's mentioned in the docs:

- https://docs.microsoft.com/en-us/azure/service-fabric/how-to-managed-cluster-configuration#enable-automatic-os-image-upgrades
- https://docs.microsoft.com/en-us/azure/service-fabric/how-to-managed-identity-managed-cluster-virtual-machine-scale-sets#add-managed-identity-properties-to-node-type-definition

But not present in this repo: https://github.com/Azure/azure-rest-api-specs/tree/master/specification/servicefabric/resource-manager/Microsoft.ServiceFabric/stable

Start by comparing the two linked Azure Service Fabric documentation pages with the specification/servicefabric/resource-manager/Microsoft.ServiceFabric/stable directory. Identify how the 2021-05-01 version should be represented there; done means that version is present in the repository's Service Fabric stable specifications and matches the documented API surface.

Written by the indexing model from the issue text.