RD Session Collection High availability - numberOfWebGwInstances suggested change

_From @fberson on December 1, 2016 14:59_

The RD Session Collection High availability adds additional VM’s with the RD Gateway and RD Web Access role, if I specify **2** as the **numberOfWebGwInstances** it creates 2 additional VM’s. I think this will confuse users as they would probably expect that 1 additional VM would be created because there already is 1 VM with those roles created using the RDS farm deployment template.

I would suggest to change the name of the first RD Gateway server to have that created with a postfix -01 and that this templates adds an RD Gateway server with postfix -02, also see #13

_Copied from original issue: mmarch/rds-templates#19_