don't add fan chart shading to legends

src/@report_series/writeSeriesForGraph.m

@@ -128,7 +128,7 @@ if ~isempty(o.graphFanShadeColor)
     assert(isint(series_num) && series_num > 1, ['@report_series.writeSeriesForGraph: can only add '...
                                                  'graphFanShadeColor and graphFanShadeOpacity starting from the ' ...
                                                  'second series in the graph']);
-    fprintf(fid, '\\addplot[%s!%d] fill between[of=%d and %d];\n', ...
+    fprintf(fid, '\\addplot[%s!%d, forget plot] fill between[of=%d and %d];\n', ...
             o.graphFanShadeColor, o.graphFanShadeOpacity, series_num, series_num - 1);
 end
 end