KDB Mount: Fix warning reported by `ronn`
- Where `path` is the path to the file the user wants to mount.
See `kdb info resolver` for details what an absolute and relative path means.
See also IMPORTANT below.
+
- `mountpoint` is where in the key database the new backend should be mounted.
For a cascading mount point, `mountpoint` should start with `/`.
See also IMPORTANT below.
+
- A list of such plugins with a configuration for each of them can be given:
- `plugin` should be an Elektra plugin.
- Plugins may be followed by a `,` separated list of `keys=values` pairs which will be used as plugin configuration.
