Document the documentation: best practices guide for docs?

[EllieKallmier]

Could be useful to:

1. New devs/contributors
2. Those using agentic or other AI tools to help write documentation
   to have a clear guide for how documentation should be approached as part of the integrated process of contribution.

Documenting the simple stuff like:

• What docstring format to use/when to apply different levels of detail
• Whose responsibility/when to update formal docs - e.g. does it have to be packaged alongside feature PRs? Or only at version updates?
• Structure for documenting bits with ISP version differences
• Template(s) where they make sense (e.g. table docs)

Just to have that written down somewhere for reference could be useful.

[EllieKallmier]

From discussion: Choose your own adventure (document as you like/how you like as you go) BUT "the feature isn't done until it's documented".