Hello Ddevis,
You are correct that you do not have to configure STP since the VCS fabric and the Nexus switches will only see a single link between them,
That said, a number of customers still configure either STP or some other loop detection protocol, so that if a loop is created (accidentally) it does not cause trouble. Whether you wish to go down this path, probably depends on the likelihood of this happening and size of the network.
Within VCS, you have a number of options for loop detection, including STP, Edge loop detection (ELD) and MAC move detection. Which you would use depends on the version of NOS you are running and probably the size of the network.
Regards
Steve