Update hello_collision.adoc

Fixed broken horizontal rule.

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

@@ -505,6 +505,7 @@ You have learned how to load a “solid physical scene model and walk around in
 You learned to speed up the physics calculations by using the CollisionShapeFactory to create efficient CollisionShapes for complex Geometries. You know how to add PhysicsControls to your collidable geometries and you register them to the PhysicsSpace. You also learned to use `player.setWalkDirection(walkDirection)` to move collision-aware characters around, and not `setLocalTranslation()`.
 
 Terrains are another type of scene in which you will want to walk around. Let's proceed with learning <<jme3/beginner/hello_terrain#,how to generate terrains>> now. 
+
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 Related info: