[FR] tab titles of index notes should display folder name, not index note title

[FynnFreyer]

E.g. my index note name is README, the title for an index note in Some/Folder should display as Folder/ (Folder would be suitable as well, but I'd prefer the trailing slash as visual indicator).

I've hacked this together here. If you're interested, I'd integrate this with the plugin and send a PR. I imagine a tick box in the settings to activate the behaviour.