[media] doc-rst: increase depth of the main index

It is useful to have an index with all the book contents somewhere,
as it makes easier to seek for something. So, increase maxdepth
to 5 for the main index at the beginning of the book.

While here, remove the genindex content, as it is bogus.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/media_uapi.rst

@@ -15,8 +15,10 @@ the license is included in the chapter entitled "GNU Free Documentation
 License".
 
 
+.. contents::
+
 .. toctree::
-    :maxdepth: 1
+    :maxdepth: 5
 
     intro
     uapi/v4l/v4l2
@@ -26,10 +28,3 @@ License".
     uapi/cec/cec-api
     uapi/gen-errors
     uapi/fdl-appendix
-
-.. only:: html
-
-  Retrieval
-  =========
-
-  * :ref:`genindex`