[HttpFoundation] Add Laravel as a backer to the README

Author: nicolas-grekas

README.md

@@ -4,6 +4,16 @@ HttpFoundation Component
 The HttpFoundation component defines an object-oriented layer for the HTTP
 specification.
 
+Sponsor
+-------
+
+The HttpFoundation component for Symfony 5.4/6.0 is [backed][1] by [Laravel][2].
+
+Laravel is a PHP web development framework that is passionate about maximum developer
+happiness. Laravel is built using a variety of bespoke and Symfony based components.
+
+Help Symfony by [sponsoring][3] its development!
+
 Resources
 ---------
 
@@ -12,3 +22,7 @@ Resources
  * [Report issues](https://github.com/symfony/symfony/issues) and
    [send Pull Requests](https://github.com/symfony/symfony/pulls)
    in the [main Symfony repository](https://github.com/symfony/symfony)
+
+[1]: https://symfony.com/backers
+[2]: https://laravel.com/
+[3]: https://symfony.com/sponsor