Update particle_emitters.adoc

Changed configure parameter table column width to 15,25,20,40 to make 4th column more readable.

src/docs/asciidoc/jme3/advanced/particle_emitters.adoc

@@ -66,7 +66,7 @@ Choose one of the following mesh shapes
 == Configure Parameters
 
 Not all of these parameters are required for all kinds of effects. If you don't specify one of them, a default value will be used.
-[cols="20,25,20,35", options="header"]
+[cols="15,25,20,40", options="header"]
 |===
 
 <a| Parameter