Expand yaml examples

[djwfyi]

Provide copy/paste yaml examples for various uses of volume claims.

DirectPV is meant for databases, data stores and data processing systems that require local drive access without the overhead of RAID or EC. For those services, we need volume claim example YAMLs.

• Single PV
• Multiple PVs per pod
• Multiple PVs across multiple pods (common case for distributed data stores).

Installation and administration of DirectPV is separate from consumption of DirectPV.
We need the docs to show how to consume DirectPV, too.