[media] doc-rst: fix the Z16 format definition

Changeset 811c6d6a ("[media] V4L: fix the Z16 format definition")
fixed the definition for DocBook, but we need to replicate it
also to ReST.
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/uapi/v4l/pixfmt-z16.rst

@@ -8,7 +8,7 @@ V4L2_PIX_FMT_Z16 ('Z16 ')
 
 *man V4L2_PIX_FMT_Z16(2)*
 
-Interleaved grey-scale image, e.g. from a stereo-pair
+16-bit depth data with distance values at each pixel
 
 
 Description