change to xref

docs/modules/tutorials/pages/beginner/hello_collision.adoc

@@ -268,7 +268,7 @@ As usual, you initialize the game in the `simpleInitApp()` method.
 
 Currently, jMonkeyEngine has two versions of link:https://pybullet.org/wordpress/[Bullet Physics]. A java port, link:http://jbullet.advel.cz/[jBullet], and link:https://en.wikipedia.org/wiki/Java_Native_Interface[JNI] (native) implementation. Although both accomplish the same goal of adding physics to your game, how you interact with each is quite different. This tutorial and it's examples use the JNI (native) implementation of physics. Which you choose is up to you.
 
-See the <<jme3/jme3_source_structure#physics, source structure>> page for details on how to add each library to your game.
+See the xref:ROOT:jme3/jme3_source_structure.adoc#physics[source structure] page for details on how to add each library to your game.
 
 How you initialize each is the same, only the methods used for manipulating objects is different. The first thing you do in every physics game is create a BulletAppState object. It gives you access to the jME3 Bullet integration which handles physical forces and collisions.
 
@@ -551,13 +551,9 @@ Again, do not use `setLocalTranslation()` to walk the player around. You will ge
 You have learned how to load a "`solid`" physical scene model and walk around in it with a first-person perspective.
 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.
+*See also:*
 
-'''
-
-Related info:
-
-*  How to load models and scenes: <<jme3/beginner/hello_asset#,Hello Asset>>, <<sdk/scene_explorer#,Scene Explorer>>, <<sdk/scene_composer#,Scene Composer>>
-*  <<jme3/advanced/terrain_collision#,Terrain Collision>>
-*  To learn more about complex physics scenes, where several mobile physical objects bump into each other, read <<jme3/beginner/hello_physics#,Hello Physics>>.
+*  How to load models and scenes: xref:beginner/hello_asset.adoc[Hello Asset], xref:ROOT:sdk/scene_explorer.adoc[Scene Explorer], xref:ROOT:sdk/scene_composer.adoc[Scene Composer].
+*  xref:ROOT:jme3/advanced/terrain_collision.adoc[Terrain Collision]
+*  To learn more about complex physics scenes, where several mobile physical objects bump into each other, read xref:beginner/hello_physics.adoc[Hello Physics].
 *  FYI, there are simpler collision detection solutions without physics, too. Have a look at link:https://github.com/jMonkeyEngine/jmonkeyengine/blob/master/jme3-examples/src/main/java/jme3test/collision/TestTriangleCollision.java[jme3test.collision.TestTriangleCollision.java].