Tell all concrete implementations to be private / not show in the docs

Oqtane.Client/Services/TenantService.cs

@@ -3,10 +3,12 @@ using System.Net.Http;
 using System.Threading.Tasks;
 using System.Collections.Generic;
 using System.Linq;
+using Oqtane.Documentation;
 using Oqtane.Shared;
 
 namespace Oqtane.Services
 {
+    [PrivateApi("Don't show in the documentation, as everything should use the Interface")]
     public class TenantService : ServiceBase, ITenantService
     {
         private readonly SiteState _siteState;