Are there some detail guide for VNFD template?

Resently, I has been using OPNFV+tacker to build a NFV platform, and test the tacker service.
There are some questions about the VNFD template:
1. I have two compute notes, and how can I deploy a VNF to a specified compute node.
    eg. deploy VNF1 to compute node 1, deploy VNF2 to compute node 2.
2. in the samples, I find the VNFD content as follow:
     config:
      param0: key0
      param1: key1
   what is the purpose of these configuration ?

Now, about VNFD template, there is not a detail guide, to explain how many VDU parameters can we config.
The information from the tacker/devstack/samples/ and http://docs.openstack.org/developer/tacker/devref/vnfd_template_parameterization.html are not enough.