Suggested cosmetic change using tags to improve readability in Visual Studio

_From @fberson on December 1, 2016 15:1_

For most of the resources that these templates create a variable, parameter of function is used to construct the name of the resources. This makes sense and I usually do that too, however is does have a small negative effect on the readability in for example Visual Studio. Objects names are not resolved at this point.
An easy way to accomplish this is by adding a tag in the resource

```
{
"apiVersion": "[variables('apiVersion')]",
"type": "Microsoft.Compute/virtualMachines",
"name": "[concat(parameters('RDGWHostNamePrefix'),'0', copyindex(1))]",
"tags": {
"displayName": "RD Gateway Virtual Machines"
},
```

This improves readability in Visual Studio, as per example below. Again, this is in no way critical but it helps to interpret resources in Visual Studio by others

_Copied from original issue: mmarch/rds-templates#20_