docs: add README to Symfony integration

Author: PedroTroller

src/Framework/Symfony/README.md

@@ -0,0 +1,9 @@
+KNP Labs - Snappy / Symfony bundle
+==================================
+
+This package integrates Snappy with the Symfony framework.
+
+![](https://img.shields.io/badge/8.1-white?style=for-the-badge&logoColor=%238993BE&label=php&labelColor=%238993BE&color=gray)
+![](https://img.shields.io/badge/8.2-white?style=for-the-badge&logoColor=%238993BE&label=php&labelColor=%238993BE&color=gray)
+![](https://img.shields.io/badge/8.3-white?style=for-the-badge&logoColor=%238993BE&label=php&labelColor=%238993BE&color=gray)
+![](https://img.shields.io/badge/8.4-white?style=for-the-badge&logoColor=%238993BE&label=php&labelColor=%238993BE&color=gray)