Add OS-specific alternative notes

plugins/nmount

@@ -4,10 +4,15 @@
 #              If the device is not mounted, it will be mounted.
 #              If the device is mounted, it will be unmounted and powered down.
 #
+# Note: The script uses Linux-specific lsblk to list block devices. Alternatives:
+#       macOS: "diskutil list"
+#       BSD: "geom disk list"
+#
 # Shell: POSIX compliant
 # Author: Arun Prakash Jana
 
 lsblk
+
 echo
 echo "Make sure you aren't still in the mounted device."
 echo -n "device (e.g. sdc2): "