Simplify installation

[gregorgorjanc]

See https://packaging.python.org/tutorials/installing-packages, in particular https://packaging.python.org/tutorials/installing-packages/#source-distributions-vs-wheels to install from the source, but we should support installation via pip etc.

Or build docs as shown here https://github.com/AlphaGenes/AlphaPlantImpute2/blob/master/README.md

[gregorgorjanc]

We should follow what @XingerTang did for https://github.com/AlphaGenes/AlphaPeel