Update README.md

Change to the code example.  The code added is at least needed for non-DI, and at least needed for .net 6.0.

README.md

@@ -580,6 +580,7 @@ some interface `ITenantProvider` and has a data store `IAuthTokenStore` that can
     {
          this.tenantProvider = tenantProvider ?? throw new ArgumentNullException(nameof(tenantProvider));
          this.authTokenStore = authTokenStore ?? throw new ArgumentNullException(nameof(authTokenStore));
+         InnerHandler = new HttpClientHandler();
     }
 
     protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
@@ -1213,4 +1214,4 @@ Note that exceptions raised when attempting to deserialize the response are not
 
 For users of [Serilog](https://serilog.net), you can enrich the logging of `ApiException` using the
 [Serilog.Exceptions.Refit](https://www.nuget.org/packages/Serilog.Exceptions.Refit) NuGet package. Details of how to
-integrate this package into your applications can be found [here](https://github.com/RehanSaeed/Serilog.Exceptions#serilogexceptionsrefit).
+integrate this package into your applications can be found [here](https://github.com/RehanSaeed/Serilog.Exceptions#serilogexceptionsrefit).