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/v4l/selection-api-003.rst

@@ -0,0 +1,20 @@
+.. -*- coding: utf-8; mode: rst -*-
+
+*****************
+Selection targets
+*****************
+
+
+.. _sel-targets-capture:
+
+.. figure::  selection-api-003_files/selection.*
+    :alt:    selection.png
+    :align:  center
+
+    Cropping and composing targets
+
+    Targets used by a cropping, composing and scaling process
+
+
+
+See :ref:`v4l2-selection-targets` for more information.