Add missing required files for Decart platform bridge

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Author: OskarStark

src/platform/src/Bridge/Decart/README.md

@@ -0,0 +1,12 @@
+Decart Platform
+===============
+
+Decart platform bridge for Symfony AI.
+
+Resources
+---------
+
+ * [Contributing](https://symfony.com/doc/current/contributing/index.html)
+ * [Report issues](https://github.com/symfony/ai/issues) and
+   [send Pull Requests](https://github.com/symfony/ai/pulls)
+   in the [main Symfony AI repository](https://github.com/symfony/ai)