[Add]: Mainsail

[ChaosBlades]

Short description of the app

Mainsail makes Klipper (3D Printer Firmware) more accessible by adding a lightweight, responsive web user interface, centred around an intuitive and consistent design philosophy.

Sources

https://docs.mainsail.xyz/setup/docker

https://github.com/mainsail-crew/mainsail/pkgs/container/mainsail

I've read and agree with the following

• [X] I've checked all open and closed issues and my request is not there.
• [X] I've checked all open and closed pull requests and my request is not there.
• [X] I've checked the website and my request is not there.