media: docs: Document metadata format in struct v4l2_format

The format fields in struct v4l2_format were otherwise documented but the
meta field was missing. Document it.

Reported-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/media/uapi/v4l/dev-meta.rst

@@ -40,7 +40,7 @@ To use the :ref:`format` ioctls applications set the ``type`` field of the
 the desired operation. Both drivers and applications must set the remainder of
 the :c:type:`v4l2_format` structure to 0.
 
-.. _v4l2-meta-format:
+.. c:type:: v4l2_meta_format
 
 .. tabularcolumns:: |p{1.4cm}|p{2.2cm}|p{13.9cm}|
 

Documentation/media/uapi/v4l/vidioc-g-fmt.rst

@@ -132,6 +132,11 @@ The format as returned by :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` must be identical
       - ``sdr``
       - Definition of a data format, see :ref:`pixfmt`, used by SDR
 	capture and output devices.
+    * -
+      - struct :c:type:`v4l2_meta_format`
+      - ``meta``
+      - Definition of a metadata format, see :ref:`meta-formats`, used by
+	metadata capture devices.
     * -
       - __u8
       - ``raw_data``\ [200]