Document backwards compat for passthru methods
Document backwards compat for passthru methods

This adds a section to the vendor-passthru documentation
about backwards compatibility (which isn't necessary but
desirable) for vendor-passthru methods.

Change-Id: I27b4a6638772e3508e9dab34d90ca904198352f0

SauloAislan/ironic,dims/ironic,bacaldwell/ironic,bacaldwell/ironic,pshchelo/ironic,devananda/ironic,NaohiroTamura/ironic,openstack/ironic,ionutbalutoiu/ironic,pshchelo/ironic,ionutbalutoiu/ironic,SauloAislan/ironic,openstack/ironic,NaohiroTamura/ironic,dims/ironic