Add note about tuning crystal w VNA

Hardware/keyboard_controller/USB_interface.kicad_sch

@@ -1836,6 +1836,16 @@
 		)
 		(uuid "7ca40df1-d61a-4c55-90ca-9c271a169209")
 	)
+	(text "Should verify C_{s} on board and adjust tuning caps\nGood excuse to get the VNA out!"
+		(exclude_from_sim no)
+		(at 41.402 140.716 0)
+		(effects
+			(font
+				(size 1.27 1.27)
+			)
+		)
+		(uuid "cf240c2a-75ce-4e1c-898f-7370d3a54cce")
+	)
 	(text "12k 1%"
 		(exclude_from_sim no)
 		(at 79.502 119.634 0)