Document build and runtime dependencies for Archlinux

[nsajko]

The README.md currently fails to mention any software dependencies (except Qt in general).

These packages from the official Archlinux repositories were required for me to build and start Graphia: qt5-base qt5-3d qt5-declarative qt5-quick3d qt5-quickcontrols qt5-quickcontrols2 qt5-graphicaleffects qt5-svg (I'm not sure that each one was necessary, though. And I may have missed some dependencies.)

EDIT: another thing that should be documented are the dependencies on the GPU stack. E.g., if Graphia uses Vulkan (I don't know if it does), there are probably additional packages that I need to install.

[bgamari]

It would be very much appreciated if the README were more precise about the build dependencies. I have nearly given up trying to package Graphia on NixOS since I have been unable to find an adequate set of dependencies.

[timangus]

There shouldn't really be any dependencies beyond Qt 5 as far as I can remember. Any libraries are in tree.