mount: add --mkdir example (#9555)

* mount: add --mkdir example

* remove unneeded space

* Update pages/common/mount.md

pages/common/mount.md

@@ -11,6 +11,10 @@
 
 `mount -t {{filesystem_type}} {{path/to/device_file}} {{path/to/target_directory}}`
 
+- Create a specific directory if it does not exist and mount a device to it:
+
+`mount --mkdir {{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}}`