Merge the API docs; get rid of the 01 naming convention

[nonprofittechy]

This will need some tweaks to how we use pymarkdown, but see:

https://docusaurus.io/docs/markdown-features/react#importing-markdown

[samglover]

I agree. This was a short-term fix for duplicate page/file names.

This is sort-of related to #415, as well.