Adds notes

src/Umbraco.Infrastructure/CompositionExtensions_Essentials.cs

@@ -20,6 +20,10 @@ namespace Umbraco.Core
         /// These services are all either created by the runtime or used to construct the runtime
         /// </remarks>
         public static void RegisterEssentials(this Composition composition,
+            // TODO: Configs should be here too, the reason is that we only register them before the Core Runtime in aspnetcore
+            // then we pre-resolve them which means that the instance re-resolved later is different... BUT if we register that
+            // pre-resolved instance here again, then it will be the same instance re-resolved later, just like we are doing with
+            // IDbProviderFactoryCreator.
             ILogger logger, IProfiler profiler, IProfilingLogger profilingLogger,
             IMainDom mainDom,
             AppCaches appCaches,

src/Umbraco.Web.Common/Extensions/UmbracoCoreServiceCollectionExtensions.cs

@@ -183,11 +183,17 @@ namespace Umbraco.Extensions
                 x.GetServices<IEmbeddedDatabaseCreator>()
             ));
 
+            // TODO: We want to avoid pre-resolving a container as much as possible we should not
+            // be doing this any more than we are now. The ugly part about this is that the service
+            // instances resolved here won't be the same instances resolved from the container
+            // later once the true container is built. However! ... in the case of IDbProviderFactoryCreator
+            // it will be the same instance resolved later because we are re-registering this instance back
+            // into the container. This is not true for `Configs` but we should do that too, see comments in
+            // `RegisterEssentials`.
             var serviceProvider = services.BuildServiceProvider();
             var configs = serviceProvider.GetService<Configs>();
             var dbProviderFactoryCreator = serviceProvider.GetRequiredService<IDbProviderFactoryCreator>();
 
-
             CreateCompositionRoot(services,
                 configs,
                 webHostEnvironment,