Teach the user to write the command lazy loading

A lazy loaded command is instantiated only when it is called.

console.rst

@@ -35,6 +35,9 @@ want a command to create a user::
 
  class CreateUserCommand extends Command
  {
+ // the name of the command (the part after "bin/console")
+ protected static $defaultName = 'app:create-user';
+
  protected function configure()
  {
  // ...
@@ -56,10 +59,6 @@ method. Then you can optionally define a help message and the
  // ...
  protected function configure()
  {
- $this
- // the name of the command (the part after "bin/console")
- ->setName('app:create-user')
-
  // the short description shown while running "php bin/console list"
  ->setDescription('Creates a new user.')