change links to point to bookmarks in contributions page

docs/modules/contributions/nav.adoc

@@ -15,8 +15,8 @@
 *** xref:ai/steer_behaviours.adoc[Steer Behaviours]
 *** xref:ai/jme3_ai.adoc[jME3 Artificial Intelligence]
 ** xref:gui/topic_contributions_gui.adoc[GUI]
-*** xref:gui/contributions.adoc#lemur-gui-library[Lemur - a native jME3 GUI library with scene graph tools]
-*** xref:gui/tonegodgui/tonegodgui.adoc#tonegodgui[tonegodGUI - a native jME3 GUI library]
+*** xref:contributions.adoc#lemur-gui-library[Lemur - a native jME3 GUI library with scene graph tools]
+*** xref:contributions.adoc#tonegodgui[tonegodGUI - a native jME3 GUI library]
 ** Tools
 *** xref:tools/navigation.adoc[Mercator Projection Tool (Marine Navigation)]
 *** xref:tools/charts.adoc[Visualizing Maps in JME3 (Marine Charts)]