Updated the warning with a note about return types

Author: WyriHaximus

README.md

@@ -42,5 +42,6 @@ $server = new Server(new MiddlewareRunner([
 # Warning
 
 This adapter rewrite the code of the PSR-15 middleware during the constructor phase, wrapping all `$delegate->process($request)`
-calls into a yield `(yield $delegate->process($request))`. This should work for most middleware but cannot be guaranteed for all.
-In case you run into issues please open an issue with the middleware in question you're having problems with.
+calls into a yield `(yield $delegate->process($request))` and striping all return types. This should work for most middleware 
+but cannot be guaranteed for all. In case you run into issues please open an issue with the middleware in question you're having 
+problems with.