added AboutAssets.txt to Maui project and changed assembly references to Oqtane 4.0.0

Oqtane.Maui/Resources/Raw/AboutAssets.txt

@@ -0,0 +1,15 @@
+Any raw assets you want to be deployed with your application can be placed in
+this directory (and child directories). Deployment of the asset to your application
+is automatically handled by the following `MauiAsset` Build Action within your `.csproj`.
+
+    <MauiAsset Include="Resources\Raw\**" LogicalName="%(RecursiveDir)%(Filename)%(Extension)" />
+
+These files will be deployed with you package and will be accessible using Essentials:
+
+    async Task LoadMauiAsset()
+    {
+        using var stream = await FileSystem.OpenAppPackageFileAsync("AboutAssets.txt");
+        using var reader = new StreamReader(stream);
+
+        var contents = reader.ReadToEnd();
+    }