mount: add example of mounting for a specific user (#9572)

pages/common/mount.md

@@ -15,6 +15,10 @@
 
 `mount --mkdir {{path/to/device_file}} {{path/to/target_directory}}`
 
+- Mount a device to a directory for a specific user:
+
+`mount -o uid={{user_id}},gid={{group_id}} {{path/to/device_file}} {{path/to/target_directory}}`
+
 - Mount a CD-ROM device (with the filetype ISO9660) to `/cdrom` (readonly):
 
 `mount -t {{iso9660}} -o ro {{/dev/cdrom}} {{/cdrom}}`