mono-docs: Add descriptions to event args

Event args structs had fields without description (missing <value> tag).

src/bin/eolian_mono/eolian/mono/events.hh

@@ -253,6 +253,7 @@ struct event_argument_wrapper_generator
                           << "[Efl.Eo.BindingEntity]\n"
                           << "public class " << name_helpers::managed_event_args_short_name(evt) << " : EventArgs {\n"
                           << scope_tab << "/// <summary>Actual event payload.</summary>\n"
+                          << scope_tab << "/// <value>" << evt.documentation.summary << "</value>\n"
                           << scope_tab << "public " << type << " arg { get; set; }\n"
                           << "}\n"
                  ).generate(sink, *etype, context);