add note about developing docs

[petrelharp]

Documenting how to get the .md files as .ipynb files, for development.

@hyanwong - do you have a better workflow than this?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.68%. Comparing base (12b196a) to head (8b51ff7).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3480      +/-   ##
==========================================
+ Coverage   91.67%   91.68%   +0.01%     
==========================================
  Files          38       38              
  Lines       32188    32232      +44     
  Branches     5151     5153       +2     
==========================================
+ Hits        29509    29553      +44     
  Misses       2346     2346              
  Partials      333      333              

Flag	Coverage Δ
C	82.23% <ø> (ø)
c-python	77.56% <ø> (+0.01%)	⬆️
python-tests	96.44% <ø> (+0.01%)	⬆️
python-tests-no-jit	33.30% <ø> (+0.10%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
Python API	98.73% <ø> (+<0.01%)	⬆️
Python C interface	91.25% <ø> (+0.01%)	⬆️
C library	91.24% <ø> (ø)

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• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[hyanwong]

I don't have a better workflow, no. I tend to develop the code in a notebook and then simply paste into the markdown file, and debug by running jupyterbook locally.

In https://tskit.dev/tutorials/intro.html we suggest running in a local notebook, but this is just done by copying the code examples from each jupyterbook cell and pasting into a new notebook cell, which is not ideal

[gregorgorjanc]

Start using Positron and you can send code to session from any text file:)

[petrelharp]

This is minor, and @hyanwong looked at it; I"m merging.