adding some information about the observability section

Author: barbara79

README.md

@@ -957,7 +957,7 @@ To migrate from the 1.x to the 2.x, there is a guideline below:
 
 ## Observability
 
-To monitor and observe the SDK, see the official documentation [Observability](https://docs.commercetools.com/sdk/observability), there is a [Demo application](https://github.com/commercetools/commercetools-sdk-php-v2/tree/master/examples/symfony-app) which shows how to monitor the PHP SDK with New Relic and Datadog.
+To monitor and observe the SDK, see the official documentation [Observability](https://docs.commercetools.com/sdk/observability), there is a [Demo application](https://github.com/commercetools/commercetools-sdk-php-v2/tree/master/examples/) which shows how to monitor the PHP SDK with New Relic, Datadog, Dynatrace and Open Telemetry.
 
 To monitor and observe the SDK, refer to the official documentation on [Observability](https://docs.commercetools.com/sdk/observability).