add description for web-based file managers, single-click/drag-and-drop upload categories

- add relation to groupware category
- ref. https://github.com/awesome-selfhosted/awesome-selfhosted/issues/2984

README.md

@@ -948,6 +948,8 @@ Network distributed filesystems.
 
 **[`^        back to top        ^`](#)**
 
+Simplified file servers for sharing of one-time/short-lived/temporary files, providing single-click or [drag-and-drop](https://en.wikipedia.org/wiki/Drag_and_drop) updload functionality.
+
 - [ass](https://github.com/tycrek/ass) - The superior self-hosted ShareX server. For use with clients such as ShareX (Windows), Flameshot (Linux), & MagicCap (Linux, macOS). `ISC` `Nodejs`
 - [Chibisafe](https://lolisafe.moe/) - Blazing fast file uploader and awesome bunker written in node. ([Source Code](https://github.com/weebdev/chibisafe)) `MIT` `Nodejs`
 - [Coquelicot](https://coquelicot.potager.org/) - Coquelicot is a “one-click” file sharing web application with a focus on protecting users’ privacy. ([Source Code](https://coquelicot.potager.org/dist/coquelicot-0.9.6.tar.gz)) `AGPL-3.0` `Ruby`
@@ -989,6 +991,10 @@ Network distributed filesystems.
 
 **[`^        back to top        ^`](#)**
 
+Web-based [file managers](https://en.wikipedia.org/wiki/File_manager).
+
+_Related: [Groupware](#groupware)_
+
 - [Apaxy](https://oupala.github.io/apaxy/) - Theme built to enhance the experience of browsing web directories, using the mod_autoindex Apache module and some CSS to override the default style of a directory listing. ([Source Code](https://github.com/oupala/apaxy)) `GPL-3.0` `HTML`
 - [DirectoryLister](https://www.directorylister.com/) - Simple PHP based directory lister that lists a directory and all its sub-directories and allows you to navigate there within. ([Source Code](https://github.com/DirectoryLister/DirectoryLister)) `MIT` `PHP`
 - [filebrowser](https://filebrowser.org/) - Web File Browser with a Material Design web interface. ([Source Code](https://github.com/filebrowser/filebrowser)) `Apache-2.0` `Go`