fix links

docs/modules/ROOT/pages/jme3/contributions.adoc

@@ -127,7 +127,7 @@ a| Yes
 === Shaderblow
 
 [.right.text-left]
-image::sdk/plugin/glass-shader.png[glass-shader.png,width="150",height=""]
+image::sdk:plugin/glass-shader.png[glass-shader.png,width="150",height=""]
 
 The "`Shaderblow`" library contains various shader effects, e.g. refraction, particles, forceshields, grayscale and much more.