docs: deprecate kernel-doc-nano-HOWTO.txt
Now that the new Sphinx world order is taking over, the information in
kernel-doc-nano-HOWTO.txt is outmoded. I hate to remove it altogether,
since it's one of those files that people expect to find. But we can add a
warning and fix all the other pointers to it.
Reminded-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
au <nbd@nbd.name>
Cc: stable@vger.kernel.org # 4.6+
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>