wxGUI/vnet: add screenshot to the manual, link to network topic

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@57894 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/docs/wxGUI.vnet.html

@@ -3,7 +3,7 @@
 
 <h2>DESCRIPTION</h2>
 
-<em>Vector Network Analysis Tool</em> is graphical front-end
+<b>Vector Network Analysis Tool</b> is graphical front-end
 for <tt>v.net*</tt> modules. It allows perform network analysis
 directly in <em><a href="wxGUI.html">wxGUI</a></em> without need to
 use command line. The tool can be launched from Layer Manager
@@ -12,6 +12,13 @@ tool</i> or from Map Display toolbar <i>Analyse map &rarr; Vector
 network analysis tool</i> <img src="icons/vector-tools.png" alt="icon">.
 
 <p>
+<center>
+<img src="wxGUI_vnet.jpg" border="1" alt="Vector Network Analysis Tool">
+<br>
+Subsets for nearest centers (<em><a href="v.net.alloc.html">v.net.alloc</a></em>)
+</center>
+
+<p>
 <em>Vector Network Analysis Tool</em> currently allows you to:
 
 <ul>
@@ -83,9 +90,12 @@ vector map representing result of analysis is not rendered
 </em>
 
 <p>
+See list of <a href="topic_network.html">vector network modules</a>.
+
+<p>
 See also the
 user <a href="http://grasswiki.osgeo.org/wiki/WxGUI_Vector_Network_Analysis_Tool">wiki</a>
-page.
+page including <a href="http://grasswiki.osgeo.org/wiki/WxGUI Vector Network Analysis Tool#Video tutorial">video tutorial</a>.
 
 <h2>AUTHOR</h2>