README: Rework with subsections

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>

README.md

@@ -1,18 +1,27 @@
-Sunxi Cedrus VA backend
-=======================
+# Sunxi-Cedrus libVA Backend
 
-This libVA video driver is designed to work with the v4l2 "sunxi-cedrus" kernel
-driver. However, the only sunxi-cedrus specific part is the format conversion
-from tiled to planar, otherwise it would be generic enough to be used with other
-v4l2 drivers using the "Frame API".
+## About
 
-You can try this driver with VLC but don't forget to tell libVA to use this
-backend:
+This libVA backend is designed to work with the Sunxi-Cedrus VPU kernel driver,
+that supports the Video Engine found in most Allwinner SoCs.
+
+## Status
+
+The Sunxi-Cedrus libVA backend currently only supports MPEG2 video decoding.
+
+## Instructions
+
+In order to use the Sunxi-Cedrus libVA backend, the `sunxi_cedrus` driver has to
+be specified through the `LIBVA_DRIVER_NAME` environment variable, as such:
 
 	export LIBVA_DRIVER_NAME=sunxi_cedrus
-	vlc big_buck_bunny_480p_MPEG2_MP2_25fps_1800K.MPG
 
-Sample media files can be found here:
+A media player that supports VAAPI (such as VLC) can then be used to decode a
+video in a supported format:
+
+	vlc path/to/video.mpg
+
+Sample media files can be obtained from:
 
 	http://samplemedia.linaro.org/MPEG2/
 	http://samplemedia.linaro.org/MPEG4/SVT/