doc-rst: linux_tv/index: Rename the book name

There's no need for all caps at its name. As the book title is
now showing at the top of each page, let's use Camel Case, to
make it less bold.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/linux_tv/index.rst

@@ -3,7 +3,7 @@
 .. include:: <isonum.txt>
 
 ##############################
-LINUX MEDIA INFRASTRUCTURE API
+Linux Media Infrastructure API
 ##############################
 
 **Copyright** |copy| 2009-2016 : LinuxTV Developers