Add java doc link to Mesh

src/docs/asciidoc/jme3/advanced/mesh.adoc

@@ -12,7 +12,7 @@ ifdef::env-github,env-browser[:outfilesuffix: .adoc]
 image::jme3/dolphin-mesh.png[dolphin-mesh.png,width="",height="",align="right"]
 
 
-All visible game elements in a scene, whether it is a Model or a Shape, are made up of polygon meshes. JME3 has a com.jme3.scene.Mesh class that represents all meshes.
+All visible game elements in a scene, whether it is a Model or a Shape, are made up of polygon meshes. JME3 has a http://javadoc.jmonkeyengine.org/com/jme3/scene/Mesh.html[com.jme3.scene.Mesh] class that represents all meshes.
 
 *  Meshes are made up of triangles: `getTriangleCount(…)` and `getTriangle(…)`
 *  Each mesh has a unique ID: `getId()`