[media] doc: v4l: add documentation for selection API

This patch adds a documentation for VIDIOC_{G/S}_SELECTION ioctl. Moreover, the
patch adds the description of modeling of composing, cropping and scaling
features in V4L2. Finally, some examples are presented.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/Documentation/DocBook/media/v4l/compat.xml b/Documentation/DocBook/media/v4l/compat.xml
index 12ba262..c736380 100644
--- a/Documentation/DocBook/media/v4l/compat.xml
+++ b/Documentation/DocBook/media/v4l/compat.xml
@@ -2376,6 +2376,12 @@
         <listitem>
 	  <para>V4L2_CTRL_FLAG_VOLATILE was added to signal volatile controls to userspace.</para>
         </listitem>
+        <listitem>
+	  <para>Add selection API for extended control over cropping and
+composing. Does not affect the compatibility of current drivers and
+applications.  See <link linkend="selection-api"> selection API </link> for
+details.</para>
+        </listitem>
       </orderedlist>
     </section>
 
@@ -2500,6 +2506,9 @@
         <listitem>
 	  <para>&VIDIOC-CREATE-BUFS; and &VIDIOC-PREPARE-BUF; ioctls.</para>
         </listitem>
+        <listitem>
+	  <para>Selection API. <xref linkend="selection-api" /></para>
+        </listitem>
       </itemizedlist>
     </section>