add missing link descr to xref

docs/modules/contributions/nav.adoc

@@ -17,7 +17,7 @@
 ** xref:gui/topic_contributions_gui.adoc[GUI]
 *** 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]
-*** xref:contributions.adoc#immediate-graphical-user-interface
+*** xref:contributions.adoc#immediate-graphical-user-interface[Immediate graphical user interface]
 ** Tools
 *** xref:tools/navigation.adoc[Mercator Projection Tool (Marine Navigation)]
 *** xref:tools/charts.adoc[Visualizing Maps in JME3 (Marine Charts)]