Merge branch 'net-organize-driver-docs-by-device-type'

Jakub Kicinski says:

====================
net: organize driver docs by device type

This series finishes off what I started in
commit b255e500

 ("net: documentation: build a directory structure for drivers").
The objective is to de-clutter our documentation folder so folks
have a chance of finding relevant info. I _think_ I got all the
driver docs from the main documentation directory this time around.

While doing this I realized that many of them are of limited relevance
these days, so I went ahead and sliced the drivers directory by
technology. Those feeling nostalgic are free to dive into the FDDI,
ATM etc. docs, but for most Ethernet is what we care about.

v1:
 - simplify Intel's docs list in MAINTAINERS.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>