Clarify documentation relating to use of multiple virtual environments and tox

[gaurav]

As suggested by @turbomam in cancerDHC/ccdhmodel#75 (comment):

I think I have some verbiage about different virtual environments and the potential use of tox in the MAINTAINERS doc that could be pared down after we merge. We might be able to make the notes about initial pushes to PyPI vs subsequent pushes less convoluted, too.

One thing that would help solve this if we had GitHub tests (#99), which would contain all the instructions we need to build and test this repository, except for the sheet2linkml code (#12). But if we end up moving sheet2linkml into its own repository (#100), then we can do that there.

[turbomam]

I think this has been getting better in all of our repos thanks to

• the refactoring of ccdhmodel and sheet2linkml
• the move towards poetry instead of pipenv

[turbomam]

Closing because

• sheet2linkml uses poetry now and there's only one Pipfile in ccdhmodel
• multi-version tests for ccdhmodel work
  • locally (make test-tox)
  • and as part of GH action https://github.com/cancerDHC/ccdhmodel/blob/main/.github/workflows/tox.yml