doc_rst: rename the media Sphinx suff to Documentation/media

The name of the subsystem is "media", and not "linux_tv". Also,
as we plan to add other stuff there in the future, let's
rename also the media uAPI book to media_uapi, to make it
clearer.

No functional changes.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/uapi/dvb/dmx-get-caps.rst

@@ -0,0 +1,59 @@
+.. -*- coding: utf-8; mode: rst -*-
+
+.. _DMX_GET_CAPS:
+
+============
+DMX_GET_CAPS
+============
+
+Name
+----
+
+DMX_GET_CAPS
+
+
+Synopsis
+--------
+
+.. cpp:function:: int ioctl(fd, int request = DMX_GET_CAPS, dmx_caps_t *)
+
+
+Arguments
+---------
+
+.. flat-table::
+    :header-rows:  0
+    :stub-columns: 0
+
+
+    -  .. row 1
+
+       -  int fd
+
+       -  File descriptor returned by a previous call to open().
+
+    -  .. row 2
+
+       -  int request
+
+       -  Equals DMX_GET_CAPS for this command.
+
+    -  .. row 3
+
+       -  dmx_caps_t *
+
+       -  Undocumented.
+
+
+Description
+-----------
+
+This ioctl is undocumented. Documentation is welcome.
+
+
+Return Value
+------------
+
+On success 0 is returned, on error -1 and the ``errno`` variable is set
+appropriately. The generic error codes are described at the
+:ref:`Generic Error Codes <gen-errors>` chapter.