media: docs: kAPI docs: move them to driver-api

All those documents describe the media driver API. So, move
them to the right place within the Kernel documentation.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Documentation/driver-api/media/index.rst

@@ -30,9 +30,9 @@ For more details see the file COPYING in the source distribution of Linux.
     :maxdepth: 5
     :numbered:
 
-    kapi/v4l2-core
-    kapi/dtv-core
-    kapi/rc-core
-    kapi/mc-core
-    kapi/cec-core
-    kapi/csi2
+    v4l2-core
+    dtv-core
+    rc-core
+    mc-core
+    cec-core
+    csi2