Centralising the installation instructions to reduce update work and inconsistencies

[trichoplax]

Describe the bug We have several sets of instructions relating to various aspects of installation of a development environment and a new instance of QPixel, spread around

• Collab
• This repository (INSTALLATION.md)
• The Wiki on this repository.

This means any updates need to be made in several places, or in practice get made in one place leading to inconsistencies.

Can we review all these places and reduce duplication as much as possible, perhaps using links rather than copying and pasting instructions? Ideally each piece of information would be in only one place to reduce the risk of it becoming out of date.

[cellio]

I think we want setup instructions for this repo here on GitHub, and other things can link to it. I think the wiki is valuable as a place to put design docs and the like, but we should avoid making it a required part of an ordinary contributor's workflow. I.e. somebody trying to set up the project should be able to ignore the wiki. Can we make that happen?

[hmltn-0]

I am working on Google Sign In but that sort of led to me learning a bit more about the installation workflow. I can personally vote for some work streamlining the installation process. I can claim this task in the future if i have time. Would be very good to be able to install for development purposes more or less in a single click.