h6: recommend bullseye if gpu accel is required

systems/allwinner_h6/readme.md

@@ -45,4 +45,4 @@ some more work will be required to make the devices below working
   - sound is not working, wifi, bluetooth and sometimes even ethernet might work or might not work depending on the tv box
 - as allwinner socs always boot by default from sd card the emmc can safely be overwritten (but do a backup of the original android system via dd command beforehand - it might be useful later)
 - there are some allwinner h6 tv boxes which cannot detect the size of the memory properly (they detect more memory than there is) and others cannot detect a connected hdmi monitor properly - to make the images working with most devices the two kernel cmdline parameters are set bydefault to overcome those problems: "mem=2048M video=HDMI-A-1:e" - those options can be omitted in case a box is working well to utilize the full amount of memory and the automatic hdmi monitor detection
-- there are graphics errors due to problems with the self compiled mesa version being used on the image (the lightdm login screen is distorted and the login to the xfce session does not seem to work at all on the focal image) - installing a hopefully more stable newer self compiled version of mesa to /opt/mesa should hopefully fix this
+- there are graphics errors due to problems with the self compiled mesa version being used on the image (the lightdm login screen is distorted and the login to the xfce session does not seem to work at all on the ubuntu images) - installing a hopefully more stable newer self compiled version of mesa to /opt/mesa should hopefully fix this - in generel: if gpu accel is required, the bullseye image is definitely the better choice