misc: mark old production summary as legacy

Unless someone picks up the development of the old
production summary, it's going to stay as it is for
a long time. @veger started to work on an alternative
version of the summary page. Therefore, it is
necessary to indicate that we likely will transition
from the old summary page.

Author: shpaass

YAFC/Workspace/ProductionSummary/ProductionSummaryView.cs

@@ -324,7 +324,7 @@ public override void Rebuild(bool visualOnly = false) {
         }
 
         public override void CreateModelDropdown(ImGui gui, Type type, Project project) {
-            if (gui.BuildContextMenuButton("Create production summary (Preview)") && gui.CloseDropdown()) {
+            if (gui.BuildContextMenuButton("Create production summary (Legacy)") && gui.CloseDropdown()) {
                 ProjectPageSettingsPanel.Show(null, (name, icon) => MainScreen.Instance.AddProjectPage(name, icon, typeof(ProductionSummary), true, true));
             }
         }