Call WebApplication.CreateBuilder(args) only once (#34492)

Co-authored-by: Rick Anderson <[email protected]>
Co-authored-by: Stephen Halter <[email protected]>

Author: 3 people

aspnetcore/fundamentals/configuration/index.md

@@ -59,6 +59,8 @@ var builder = WebApplication.CreateBuilder(args);
 1. [appsettings.json](#appsettingsjson) using the [JSON configuration provider](#jcp).
 1. A fallback to the host configuration described in the [next section](#host).
 
+Note: `WebApplication.CreateBuilder(args)` should only be called once in apps relying on IIS in-process hosting.<!--Delete this note in the .NET 10 version of the article. See <https://github.com/dotnet/aspnetcore/pull/59910>. -->
+
 <a name="host"></a>
 
 ### Default host configuration sources