TASK: Add disclamer to README

As version 7 of flow is not working with this package anymore, we should inform the users in the README.

README.md

@@ -2,6 +2,17 @@
 
 Fully featured CORS HTTP component (a.k.a. middleware) for Flow framework to allow "cross-domain" requests.
 
+
+```
+⚡️ Warning
+
+This package is not working with version 7.0 and higher of the Neos/Flow framework.
+In version 7.0 we introduced PSR-15 Middlewares and it is possible to use other PHP libraries instead.
+
+For instance https://github.com/tuupola/cors-middleware
+```
+
+
 ## Background
 
 This package is a implementation of a CORS middleware for Cross-Origin Resource Sharing (see https://developer.mozilla.org/en-US/docs/Glossary/CORS).
@@ -102,4 +113,4 @@ Flowpack:
     # Debugging flag adds additional logging to System.log to debug server-side CORS issues.
     #
     debug: false
-```
+```