docs: add write example

Author: mishamyrt

README.md

@@ -34,15 +34,17 @@ import (
 )
 
 func main() {
-    // Setup HID
-    nuga.Init()
+	// Setup HID
+	nuga.Init()
 	defer nuga.Exit()
 	// Open connection with keyboard
 	device, _ := nuga.Open()
 	// Read current effects
 	effects, _ := device.Features.Light.GetEffects()
 	// Set brightness to 50%
 	effects.Backlight.SetBrightness(2)
+	// Write effects
+	_ = device.Features.Light.SetEffects(effects)
 }
 ```