Install DietPi from ChromeOS

[MichaIng]

Following these instructions by @rhkean: https://dietpi.com/phpbb/viewtopic.php?p=28402#p28402
I'm currently not 100% sure how we merge this into the docs best: https://dietpi.com/docs/install/

We have 4 types of images:

• Such which are to be flashed to the target root drive directly: All SBC images + x86_64 BIOS direct flash image
• Such which are to be flashed onto a removable drive to boot into an installer and install DietPi from there to an internal drive, like eMMC or such: Currently the x86_64 BIOS + UEFI installer images, but I plan such for SBCs with eMMC as well.
• The VirtualBox image
• The VMware image
• And, for completeness, the Hyper-V image

All images have in common that you need to download a 7z from our server and extract it. Especially the extraction can be done on different ways on different host OS'es ("host" is not really correct, I mean the system you download, extract and flash the DietPi image on), p7zip on Linux (does it work on macOS as well?), 7zip on Windows, "Wicked Good Unarchiver" on ChromeOS, "The Unarchiver" for macOS.
All but the VM images require flashing them. balenaEtcher is a GUI tools that works on all platforms, BUT ChromeOS. Also on Linux when no desktop is installed, a console tool like dd is a great alternative.

From user perspective, it's ideal when the docs are structured like a tree, e.g. you select the image type tab, then the host OS tab for extraction and flashing. For maintenance and code efficiency it would be best to have separate pages/blocks to explain how to extract a 7z and flash an img on different host systems, then linking these pages/tabs from the related section of the image type doc.

[StephanStS]

Possibly this description can be generated from the link given above and a virtual machine like a VirtualBox Chrome OS VM (installation described there).