nvml: Document helpers and OS devices
nvml: Document helpers and OS devices

Refs #71
Refs #97

This commit was SVN r5141.

ggouaillardet/hwloc,shekkbuilder/hwloc,shekkbuilder/hwloc,shekkbuilder/hwloc,ggouaillardet/hwloc,ggouaillardet/hwloc,shekkbuilder/hwloc,ggouaillardet/hwloc