scsi_mid_low_api.txt

This patch against 2.5.46-bk3 is work in progress
(since the interface is in flux). It dusts of some
cobwebs, removes politically incorrect typedefs and
describes slave_attach() and slave_detach(). It
removes the revoke() description (per hch? changes).

Is a section describing mid level functions provided
for LLDDs (e.g. scsi_adjust_queue_depth() )
warranted?