[PHPDoc] Fix some union type cases

Author: fancyweb

Process.php

@@ -132,7 +132,7 @@ class Process implements \IteratorAggregate
      * @param array          $command The command to run and its arguments listed as separate entries
      * @param string|null    $cwd     The working directory or null to use the working dir of the current PHP process
      * @param array|null     $env     The environment variables or null to use the same environment as the current PHP process
-     * @param mixed|null     $input   The input as stream resource, scalar or \Traversable, or null for no input
+     * @param mixed          $input   The input as stream resource, scalar or \Traversable, or null for no input
      * @param int|float|null $timeout The timeout in seconds or null to disable
      *
      * @throws LogicException When proc_open is not installed
@@ -183,7 +183,7 @@ public function __construct($command, string $cwd = null, array $env = null, $in
      * @param string         $command The command line to pass to the shell of the OS
      * @param string|null    $cwd     The working directory or null to use the working dir of the current PHP process
      * @param array|null     $env     The environment variables or null to use the same environment as the current PHP process
-     * @param mixed|null     $input   The input as stream resource, scalar or \Traversable, or null for no input
+     * @param mixed          $input   The input as stream resource, scalar or \Traversable, or null for no input
      * @param int|float|null $timeout The timeout in seconds or null to disable
      *
      * @return static