doc: use virtual env for installation

[thijstriemstra]

fixes #166

[rm-hull]

I tend to use:

python3 -m venv .venv
.venv/bin/activate

I think IDEs like vscode and tools like pyenv will sniff out a .venv directory and will auto-activate it.

Is there any reason not to stick to that convention?

[rm-hull]

Or are you aiming to pull all the dependencies for all sub-projects into one place?

[thijstriemstra]

Is there any reason not to stick to that convention?

I didn't know that IDEs like vscode and tools like pyenv will sniff out a .venv directory and will auto-activate it, but maybe I'm just old-skool :-/

[thijstriemstra]

Is there any reason not to stick to that convention?

I like to know where my virtual envs live, explicitly, in this case ~/luma-env, and since I didn't know about that convention (and new users wont either i'd guess) I chose this.