fix image link

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

@@ -4,7 +4,7 @@
 :revdate: 2020/07/06
 
 
-image:jme3/beginner/hellovectorsumm2.png[hellovectorsumm2.png,width="",height=""]
+image:beginner/hellovectorsumm2.png[hellovectorsumm2.png,width="",height=""]
 
 HelloVectorSumm.java