I sometimes share a folder with many different files to people (many not very computer-skilled), so I would like to have a file displayed automatically when people open a folder.
For example, look at https://github.com/nextcloud/calendar
There you have a file list, but also it display the contents of README.md with some useful information for all readers.
This way the visitor will be shown some helpful text messages instead of a bunch of files only.
I think that is a great idea, I also need this feature. An introduction to the contents of a folder would be really helpfull. And using the README.md file for that can be considered a standard.
The is a markdown editor
But it only has a preview in the sidebar after you click on a md file.