Update CONTRIBUTING.md

[robkam]

add sub-sections to Tools and mention mypy

EDIT: [added by @elsiehupp] see #173

[elsiehupp]

I added mypy and flake8 to pyproject.toml under [tool.poetry.dev-dependencies], so separate installation instructions shouldn't be necessary for them. From #197:

[tool.poetry.dev-dependencies]
pytest = "^6.2.5"
requests = "^2.31.0"
flake8 = "^3.9.2"
pre-commit = "^2.17.0"
pymarkdown = "^0.1.4"
mypy = "^1.5.1"
types-requests = "^2.31.0.2"
# flake8-black may be unnecessary?
flake8-black = "^0.3.6"

IIRC the reason to mention pre-commit as a separate installation is that it doesn't generally run inside the Poetry virtual environment, since it interacts with Git. I don't actually remember what it does (if anything) inside of Poetry.

We do need to restructure the documentation regardless, though, so certain other aspects of this PR we should continue working on. I'm gonna rename this PR and mark it as a draft because of the broader scope, and I might contribute some changes of my own.

[elsiehupp]

It looks like I should add an explanation of how to set up the correct Python virtual environment as I'm having to do for #197.

[robkam]

I'm getting out of my depth here. I'd be happy for you to finish these changes to the documentation.

Although useful to a novice, is it necesary to include 'tools to Python' in the contributing.md?

[robkam]

Closing this to tidy up. AFAICT the documentation is now adequate.