Add info to README
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-filemanager provides WebDAV features and a file managing interface within the specified directory and it can be used to upload, delete, preview, rename and edit your files within that directory.
+filemanager provides WebDAV features and a file managing interface within the specified directory and it can be used to upload, delete, preview, rename and edit your files within that directory. It is an implementation of [hacdias/filemanager](https://github.com/hacdias/filemanager) library.
It is extremely important for security reasons to cover the path of filemanager with some kind of authentication. You can use, for example, [`basicauth`](https://caddyserver.com/docs/basicauth) directive.
