doc: Fix typo in USB Gadget Documentation

Changed from "Please not that" to "Please note that"

Signed-off-by: David E. Narvaez <[e-mail]>
Acked-by: Felipe Balbi <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

Documentation/usb/gadget_multi.txt

···
 and RNDIS can be turned off.  If they are both enabled the gadget will
 have two configurations -- one with RNDIS and another with CDC ECM[3].
 
-Please not that if you use non-standard configuration (that is enable
+Please note that if you use non-standard configuration (that is enable
 CDC ECM) you may need to change vendor and/or product ID.
 
 * Host drivers