Reword popup for pre-ship PLC

Source/StartupPopup.cs

@@ -8,7 +8,7 @@ namespace RP0InstallChecker
     [KSPAddon(KSPAddon.Startup.Instantly, true)]
     public class StartupPopup : MonoBehaviour
     {
-        private const string PreferenceFileName = "RP1UpgradeWarning";
+        private const string PreferenceFileName = "RP1UpgradeWarningPre";
         private static string PreferenceFilePath => Path.Combine(
             Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location),
             "PluginData",
@@ -24,7 +24,7 @@ public void Start()
                     new Vector2(0, 0),
                     new MultiOptionDialog(
                         "RP1StartupDialog",
-                        "This is the legacy version of RP-1, and is no longer supported. There is a new version of RP-1, the Programs and Launch Complexes rework, now available. It is savebreaking, and a work in progress, but if you are starting a new save it is highly recommended to switch to that version. Please uninstall RP-1 (Legacy) and install RP-1 (PLC). You can do this by uninstalling and reinstalling the RP-1 Express Install and choosing one of the non-Legacy options.",
+                        "Stay tuned for a major update to RP-1. It should be out by the end of May 2023. Check the Discord or wiki for more info regarding the Programs and Launch Complexes rework. Note that this udpate will be save-breaking, and maintenance of Legacy RP-1 will be ending.",
                         "RP-1",
                         HighLogic.UISkin,
                         new DialogGUIVerticalLayout(