Updating vmSize description to correct hyperlinks and add a note on d…

…eprecating VirtualMachineSizeTypes enum in subsequent api-versions. (Azure#11595)

* Removing vmSizeTypes enum

* Updating description and reverting the enum removal which will be done in a new api-version as a breaking change.

Co-authored-by: Avinash Akka <avakka@microsoft.com>

specification/compute/resource-manager/Microsoft.Compute/stable/2020-06-01/compute.json

@@ -7837,7 +7837,7 @@
       "properties": {
         "vmSize": {
           "type": "string",
-          "description": "Specifies the size of the virtual machine. For more information about virtual machine sizes, see [Sizes for virtual machines](https://docs.microsoft.com/azure/virtual-machines/virtual-machines-windows-sizes?toc=%2fazure%2fvirtual-machines%2fwindows%2ftoc.json). <br><br> The available VM sizes depend on region and availability set. For a list of available sizes use these APIs:  <br><br> [List all available virtual machine sizes in an availability set](https://docs.microsoft.com/rest/api/compute/availabilitysets/listavailablesizes) <br><br> [List all available virtual machine sizes in a region](https://docs.microsoft.com/rest/api/compute/virtualmachinesizes/list) <br><br> [List all available virtual machine sizes for resizing](https://docs.microsoft.com/rest/api/compute/virtualmachines/listavailablesizes)",
+          "description": "Specifies the size of the virtual machine. For more information about virtual machine sizes, see [Sizes for virtual machines](https://docs.microsoft.com/en-us/azure/virtual-machines/sizes). <br><br> The available VM sizes depend on region and availability set. For a list of available sizes use these APIs:  <br><br> [List all available virtual machine sizes in an availability set](https://docs.microsoft.com/rest/api/compute/availabilitysets/listavailablesizes) <br><br> [List all available virtual machine sizes in a region]( https://docs.microsoft.com/en-us/rest/api/compute/resourceskus/list) <br><br> [List all available virtual machine sizes for resizing](https://docs.microsoft.com/rest/api/compute/virtualmachines/listavailablesizes). <br><br> This list of sizes is no longer updated and the **VirtualMachineSizeTypes** string constants will be removed from the subsequent REST API specification. Use [List all available virtual machine sizes in a region]( https://docs.microsoft.com/en-us/rest/api/compute/resourceskus/list) to get the latest sizes.",
           "enum": [
             "Basic_A0",
             "Basic_A1",