More complete instruction to convert image to theme

htdocs/theme/eldy/img/menus/README.md

@@ -4,9 +4,10 @@ Tutorial to create a new image for menu:
 1) First find an image.
 2) With Gimp, open image and check there is a alpha channel. If not add one.
 3) Convert image into back and white (Menu Image - Mode - Grey levels).
-4) Use the degrade tool with option:
-* Erase color
+4) Use the degrade tool with option (Menu Tools - Paint - Degrade - CTRL+L):
+* Mode: Erase color (you can also try "Elear only") 
 * Opacity: 50 +/-
 * Offset: 0
 * Shape: Linear
+* Select on image top of file and drag to bottom.
 Il est possible aussi d'augmenter la transparence globale depuis le calque.