Fixed usage docs for user-add-role. (#4088)

Author: penyaskito

src/Drupal/Commands/core/UserCommands.php

@@ -159,7 +159,7 @@ public function unblock($names)
      * @param string $role The name of the role to add.
      * @param string $names A comma delimited list of user names.
      * @aliases urol,user-add-role
-     * @usage drush user:add-role "power user" user3
+     * @usage drush user-add-role "power user" user3
      *   Add the "power user" role to user3
      */
     public function addRole($role, $names)