A need for more Documentation

At present, the documentation for dbx_build_tools is very minimal: it provides a "lightning tour" - which is no substitute for more detailed documentation that people might need when they get beyond the "hello world" stage.

This is a shame, because dbx_build_tools is the best option for a hermetic bazel python build, which makes it a better candidate than rules_python for anyone who takes hermeticity seriously. Without a more detailed README, it's hard to get to grips with, and I wonder if this means that it attracts a smaller userbase than it might otherwise do.

For example, things I'd like to know as a brand new user:

- Do I _need_ to use `bzl`? It seems to be a feature, rather than a requirement - and bringing in a new workflow that will only impact the (relatively small) python component of my project isn't attractive to me.
- How can I resolve problems when packages cannot be found? (right now I can't get any imports to work with `bzl gen`, and I don't have anywhere to look - my debug stage so far involves looking through the dbx_build_tools repo, messing around with dbx_py_pypi_piplib in a BUILD file rather than BUILD.in, and generally chasing my tail).
- I just want to focus on python3, with python2 hitting EOL over a year ago. But register_toolchains seems to need a python2.7 toolchain as well as the python3.8 toolchain that I want - why?

The documentation doesn't need to go into such details, but as things stand, it seems that such a clearly useful and well-thought-out project is being let down by the documentation. Once I get to grips with using the project I'd be happy to help on that front.