[Announcement][php-silex] Silex package is abandoned

Created by: ybelenko

Silex package has been abandoned:

This package is abandoned and no longer maintained. The author suggests using the symfony/flex package instead.

WARNING: Silex is in maintenance mode only. Ends of life is set to June 2018. Read more on Symfony's blog.

Should we mark php-silex generator as deprecated? Or we need to migrate to symfony/flex package instead?