minor #10460 Teach the user to write the command lazy loading (SimonHeimberg)

This PR was submitted for the 4.1 branch but it was squashed and merged into the 3.4 branch instead (closes #10460).

Discussion
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Teach the user to write the command lazy loading

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

Commits
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4706701 Teach the user to write the command lazy loading

Author: xabbuh

console.rst

@@ -27,6 +27,9 @@ For example, you may 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()
         {
             // ...
@@ -49,9 +52,6 @@ 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.')