fix xrefs

docs/modules/ROOT/pages/jme3/contributions/vegetationsystem/grass.adoc

@@ -1,10 +1,6 @@
 = The grass system
-:author: 
-:revnumber: 
-:revdate: 2016/03/17 20:48
-:relfileprefix: ../../../
-:imagesdir: ../../..
-ifdef::env-github,env-browser[:outfilesuffix: .adoc]
+:revnumber: 2.0
+:revdate: 2020/07/15
 
 
 Here you will learn how to use the grass system. The test project available on the project page contains enough well-commented examples to get you going, but there are some more information available here.
@@ -37,7 +33,7 @@ Here is some basic information and tips here on how to make a vegetation system
 
 Grass and foliage often use alpha textures. Alpha textures are partially (or fully) transparent. A standard alpha texture contains the RGB channels, but also an additional alpha channel where the transparency values are stored.
 
-There is a tutorial on how to work with alpha textures and transparency here: <<jme3/beginner/hello_material#,jme3:beginner:hello_material>>
+There is a tutorial on how to work with alpha textures and transparency here: xref:tutorials:beginner/hello_material.adoc[jme3:beginner:hello_material]
 
 
 === Coloring & Depth

docs/modules/ROOT/pages/jme3/quaternion.adoc

@@ -99,7 +99,7 @@ s.getLocalRotation().fromAxes(axes);
 
 === Rotation Matrix
 
-Commonly you might find yourself with a xref:jme3/matrix.adoc[Matrix] defining a xref:tutorials:rotate.adoc#[rotation]. In fact, it's very common to contain a rotation in a Matrix, create a Quaternion, rotate the Quaternion, and then get the Matrix back. Quaternion contains a `fromRotationMatrix` method that will create the appropriate Quaternion based on the given Matrix. The `toRotationMatrix` will populate a given Matrix.
+Commonly you might find yourself with a xref:jme3/matrix.adoc[Matrix] defining a xref:tutorials:intermediate/rotate.adoc#[rotation]. In fact, it's very common to contain a rotation in a Matrix, create a Quaternion, rotate the Quaternion, and then get the Matrix back. Quaternion contains a `fromRotationMatrix` method that will create the appropriate Quaternion based on the given Matrix. The `toRotationMatrix` will populate a given Matrix.
 
 
 ==== Example - Rotate a Spatial Using a Rotation Matrix