[media] DocBook: partial rewrite of "Opening and Closing Devices"

This section was horribly out of date. A lot of references to old and
obsolete behavior have been dropped.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

Documentation/DocBook/media/v4l/v4l2.xml

@@ -145,7 +145,7 @@ applications. -->
 	<revnumber>3.15</revnumber>
 	<date>2014-02-03</date>
 	<authorinitials>hv</authorinitials>
-	<revremark>Update several sections of "Common API Elements":
+	<revremark>Update several sections of "Common API Elements": "Opening and Closing Devices"
 "Querying Capabilities", "Application Priority", "Video Inputs and Outputs", "Audio Inputs and Outputs"
 "Tuners and Modulators", "Video Standards" and "Digital Video (DV) Timings".
 	</revremark>