change ubuntu OS description

[georgejhunt]

per Adam's request

[holta]

Thanks much @georgejhunt.

I'm not sure if @tim-moody will be updating this U20 image in coming days (if so presumably replacing it with IIAB 7.1's final release from this past wkd) but I'll ask him.

Then we should also add @jvonau's ~2 images into this very same: https://raw.githubusercontent.com/iiab/iiab-factory/master/box/rpi/iiab-imager/os_list_imagingutility_iiab_experimental.json

Giving us 3 images each — in each of these 2 submenus[*] — for a total of 6 IIAB images on offer:

• 3 in https://raw.githubusercontent.com/iiab/iiab-factory/master/box/rpi/iiab-imager/os_list_imagingutility_iiab_subitems.json
• 1 for now (but soon 3) in https://raw.githubusercontent.com/iiab/iiab-factory/master/box/rpi/iiab-imager/os_list_imagingutility_iiab_experimental.json

...which seems quite reasonable for now, per our IIAB weekly call (http://minutes.iiab.io) earlier this morning.

[*] These 2 sub-menus being spawned by http://iiab.me/images.json — when someone pastes in any of the Raspberry Pi Imager commands that George has documented at https://github.com/iiab/iiab/wiki/Raspberry-Pi-Images:-Summary