[media] doc-rst: add documentation for Zoran driver

Convert it to ReST and add to media/v4l-drivers book.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/v4l-drivers/index.rst

@@ -40,4 +40,5 @@ License".
 	si476x
 	soc-camera
 	uvcvideo
+	zoran
 	zr364xx