sch: add LED resistor comments

usb-microbc_cable_tester-mcu.kicad_sch

@@ -5106,6 +5106,17 @@
 		)
 		(uuid "151f5058-f9bd-431d-a843-fc4918cf60e2")
 	)
+	(text "resistors values for\nmultiplexed LEDs:\n- green: 22k\n- white: 4.7k\n- blue: 220\n- yellow: 1.0k\n- pink: 2.2k\n- UV/purple: 330"
+		(exclude_from_sim no)
+		(at 176.022 47.752 0)
+		(effects
+			(font
+				(size 1.27 1.27)
+			)
+			(justify left bottom)
+		)
+		(uuid "349283a6-67b9-4c0f-865a-9a9af0efe76d")
+	)
 	(text "0 1 boot:\n0 x flash\n1 1 loader\n1 0 RAM"
 		(exclude_from_sim no)
 		(at 50.165 66.04 0)