media: docs: move uAPI book to userspace-api/media

Since 2017, there is an space reserved for userspace API,
created by changeset 1d596dee38 ("docs: Create a user-space API guide").

As the media subsystem was one of the first subsystems to use
Sphinx, until this patch, we were keeping things on a separate
place.

Let's just use the new location, as having all uAPI altogether
will likely make things easier for developers.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Documentation/userspace-api/media/net.h.rst.exceptions

@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0
+
+# Ignore header name
+ignore define _DVBNET_H_
+
+# Ignore old ioctls/structs
+ignore ioctl __NET_ADD_IF_OLD
+ignore ioctl __NET_GET_IF_OLD
+ignore struct __dvb_net_if_old
+
+# Macros used at struct dvb_net_if
+replace define DVB_NET_FEEDTYPE_MPE :c:type:`dvb_net_if`
+replace define DVB_NET_FEEDTYPE_ULE :c:type:`dvb_net_if`