minor #29815 [Console] Fix phpdoc for InputOption shortcut (tvlooy)

This PR was submitted for the master branch but it was merged into the 3.4 branch instead (closes #29815).

Discussion
----------

[Console] Fix phpdoc for InputOption shortcut

symfony documentation tells people to pass null, and it is the default, but the method docs don't allow it so static analyzers complain about it (spotted by phan)

| Q             | A
| ------------- | ---
| Branch?       |  3.4 (careful when merging)
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Commits
-------

64a65e9 Fix docs

src/Symfony/Component/Console/Command/Command.php

@@ -388,7 +388,7 @@ public function addArgument($name, $mode = null, $description = '', $default = n
      * Adds an option.
      *
      * @param string                        $name        The option name
-     * @param string|array                  $shortcut    The shortcuts, can be null, a string of shortcuts delimited by | or an array of shortcuts
+     * @param string|array|null             $shortcut    The shortcuts, can be null, a string of shortcuts delimited by | or an array of shortcuts
      * @param int|null                      $mode        The option mode: One of the InputOption::VALUE_* constants
      * @param string                        $description A description text
      * @param string|string[]|int|bool|null $default     The default value (must be null for InputOption::VALUE_NONE)

src/Symfony/Component/Console/Input/InputOption.php

@@ -34,7 +34,7 @@ class InputOption
 
     /**
      * @param string                        $name        The option name
-     * @param string|array                  $shortcut    The shortcuts, can be null, a string of shortcuts delimited by | or an array of shortcuts
+     * @param string|array|null             $shortcut    The shortcuts, can be null, a string of shortcuts delimited by | or an array of shortcuts
      * @param int|null                      $mode        The option mode: One of the VALUE_* constants
      * @param string                        $description A description text
      * @param string|string[]|int|bool|null $default     The default value (must be null for self::VALUE_NONE)
@@ -89,7 +89,7 @@ public function __construct($name, $shortcut = null, $mode = null, $description
     /**
      * Returns the option shortcut.
      *
-     * @return string The shortcut
+     * @return string|null The shortcut
      */
     public function getShortcut()
     {