Rewrite docs with DocStringExtensions

[MilesCranmer]

Another package I wish I knew about a long time ago… https://docstringextensions.juliadocs.org/stable/

[MilesCranmer]

It seems like it’s not fully fleshed out yet. For example when using TYPEDSIGNATURES, all methods appear to return Any according to the docstring. So I will hold off on trying this for now.