Update hello_terrain.adoc

Brought the images at end of list "Now you start painting the texture:" into the list.

src/docs/asciidoc/jme3/beginner/hello_terrain.adoc

@@ -227,7 +227,7 @@ Now you start painting the texture:
 ..  Paint blue lines where you want roads to criss-cross the landscape.
 
 .  The end result should look similar to this:
-
++
 image:jme3/beginner/mountains512.png[mountains512.png,64,64] ⇒ image:jme3/beginner/alphamap.png[alphamap.png,64,64]