Organize driver documentation by device type. Most documents
have fairly verbose yet uninformative names, so let users
first select a well defined device type, and then search for
a particular driver.

While at it rename the section from Vendor drivers to
Hardware drivers. This seems more accurate, besides people
sometimes refer to out-of-tree drivers as vendor drivers.
Signed-off-by: NJakub Kicinski <kuba@kernel.org>
Acked-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: NShannon Nelson <snelson@pensando.io>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>