docs: usb: rename files to .rst and add them to drivers-api

While there are a mix of things here, most of the stuff
were written from Kernel developer's PoV. So, add them to
the driver-api book.

A follow up for this patch would be to move documents from
there that are specific to sysadmins, adding them to the
admin-guide.

Signed-off-by: Mauro Carvalho Chehab <[email protected]>
Acked-by: Johan Hovold <[email protected]>
Acked-by: Felipe Balbi <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
52 files changed