Add warning when generating network diagram about graphviz version (bug 11470)

lib/refrepo/gen/wiki/generators/site_network.rb

@@ -34,6 +34,7 @@ class SiteNetworkGenerator < WikiGenerator
     @generated_content += MW::LINE_FEED
 
     # this will generate dot and png network maps in the current directory
+    puts "WARNING : Graph generation depends on graphviz version, check the graphs before uploading it. graphviz 2.40.1-6 seems to work correctly"
     check_network_description({:sites => [@site], :dot => true})
   end
 end