fix links

docs/modules/core/pages/collision/collision_and_intersection.adoc

@@ -3,7 +3,7 @@
 :revdate: 2020/07/24
 
 
-The term collision can be used to refer to <<jme3/advanced/physics_listeners#,physical interactions>> (where xref:physics:physics.adoc[physical objects] collide, push and bump off one another), and also to non-physical _intersections_ in 3D space. This article is about the non-physical (mathematical) collisions.
+The term collision can be used to refer to xref:physics:collision/physics_listeners.adoc[physical interactions] (where xref:physics:physics.adoc[physical objects] collide, push and bump off one another), and also to non-physical _intersections_ in 3D space. This article is about the non-physical (mathematical) collisions.
 
 Non-physical collision detection is interesting because it uses less computing resources than physical collision detection. The non-physical calculations are faster because they do not have any side effects such as pushing other objects or bumping off of them. Tasks such as <<jme3/advanced/mouse_picking#,mouse picking>> are easily implemented using mathematical techniques such as ray casting and intersections.  Experienced developers optimize their games by finding ways to simulate certain (otherwise expensive physical) interactions in a non-physical way.
 

docs/modules/physics/pages/control/walking_character.adoc

@@ -128,7 +128,7 @@ bulletAppState.getPhysicsSpace().add(myCharacter_phys);
 
 [IMPORTANT]
 ====
-The BulletPhysics CharacterControl only collides with "`real`" PhysicsControls (RigidBody). It does not detect collisions with other CharacterControls! If you need additional collision checks, add GhostControls to your characters and create a custom xref:jme3/advanced/physics_listeners.adoc[collision listener] to respond.
+The BulletPhysics CharacterControl only collides with "`real`" PhysicsControls (RigidBody). It does not detect collisions with other CharacterControls! If you need additional collision checks, add GhostControls to your characters and create a custom xref:collision/physics_listeners.adoc[collision listener] to respond.
 ====
 
 

docs/modules/physics/pages/physics.adoc

@@ -8,7 +8,7 @@ A physics simulation is used in games and applications where objects are exposed
 
 The jMonkeyEngine3 has built-in support for link:http://jbullet.advel.cz[jBullet Physics] (based on link:http://bulletphysics.org[Bullet Physics]) via the `com.jme3.bullet` package. This article focuses mostly on the RigidBodyControl, but also introduces you to others.
 
-If you are looking for info on how to respond to physics events such as collisions, read about <<jme3/advanced/physics_listeners#,Physics Listeners>>.
+If you are looking for info on how to respond to physics events such as collisions, read about xref:collision/physics_listeners.adoc[Physics Listeners].
 
 
 == Technical Overview