Add note about perf to Http3SampleApp

Follow up to #58094

Author: amcasey

src/Servers/Kestrel/samples/Http3SampleApp/Program.cs

@@ -37,8 +37,8 @@ public static void Main(string[] args)
 
                     // On a machine that supports IPv6, msquic will resolve `localhost` to `::1`, which `IPAddress.Any` will not accept.
                     // (To make it work, you'd need to use `IPv6Any`, as `ListenAnyIP` does.)  As a result, a client built on msquic, 
-                    // e.g. `HttpClient` on Windows, will not be able to make HTTP/3.0 requests to `localhost:5001`.  HTTP/1.x and 
-                    // HTTP/2.0 will still work.
+                    // e.g. `HttpClient`, will not be able to make HTTP/3.0 requests to `localhost:5001`.  HTTP/1.x and HTTP/2.0 will
+                    // still work, but will be slower than necessary since they will try and fail the resolved IPv6 address first.
                     // Example: https://github.com/dotnet/runtime/issues/108259
                     // msquic: https://github.com/microsoft/msquic/issues/1181 (resolve both)
                     // System.Net.Quic: https://github.com/dotnet/runtime/issues/82404 (improve consistency with sockets)