Minor fix in Secrets example

DefensiveProgramming/Secrets/Program.cs

@@ -11,7 +11,7 @@ IConfiguration configuration = new ConfigurationBuilder()
                                    .AddJsonFile("appsettings.json")   //order is important!
                                    .AddJsonFile("missing_one.json", optional: true)   //
                                    .AddEnvironmentVariables()    // include Package Microsoft.Extensions.Configuration.EnvironmentVariables                                     
-                                   .AddUserSecrets("PI-Secrets") //package Microsoft.Extensions.Configuration.UserSecrets
+                                   .AddUserSecrets<Program>() //package Microsoft.Extensions.Configuration.UserSecrets
                                    .Build();
 
 Console.WriteLine($"Custom env variable using configuration = " + configuration["CustomEnvValue"]);