[update] mate desktop has been chosen to be default gui

for completeness, i will add that the main thing to note regarding the choice of desktop for the ISO and installer, is that the install process on all archiso-based ISOs has always been entirely independent from the live environment; so it is not essential to consider any one desktop environment as "THE" official parabola desktop or even to have any one prescribed default option - i am currently working to make the calamares installer capable of installing the user's choice of desktop (or none at all) and perhaps with the user's choice of init system as well - in that way we can continue adding more install options without increasing the number of ISO variants

regarding the mate desktop: up until about six months ago, parabola graphical LiveISOs had the mate desktop, but since mate's move to GTK3, there are problems getting it to work well on a liveISO, which is why we chose to replace it with LXDE instead - that being said, mate still works well once fully installed and is already one of the options in the calamares graphical installer