document roxie HELM support for "directAccessPlanes"

A new helm values entry for roxie, "directAccessPlanes" allows the user to specify a list of storage planes that roxie will read data from without copying to it's default storage plane.

Normally if roxie finds data on a storage plane that is not it's default storage plane it will access the content from there and copy it to its default storage plane.

Adding the source plane to roxie's list of directAccessPlanes will prevent roxie from copying the file to its default plane.  Planes in directAccessPlanes are considered close enough and acceptable for roxie to use directly.

roxie:
  directAccessPlanes: [ dataplane3 ]