A very simply solution would be to create a ReadMe file for each folder, either as a simple text format or
Markdown format [
https://www.markdownguide.org/]. This could describe the purpose of the folder. However, that wouldn't include a dynamic list of the files in the folder.
Alternatively, if you are documenting source code, perhaps you could use a documentation tool (e.g.
Doxygen [
https://doxygen.nl/index.html]). That particular tool has a
command [
https://www.doxygen.nl/manual/commands.html#cmddir] to document the containing folder.
Neither of these solutions is especially related to Subversion. Given that you've asked the question here, perhaps you had specific Subversion capabilities that you wanted to consider further. If you are more specific, perhaps someone will have suggestions that relate more to Subversion.
Hope this helps.