Added warning about externalId change

Signed-off-by: rschouten97 <[email protected]>

README.md

@@ -1,7 +1,12 @@
+| :warning: Warning |
+|:---------------------------|
+| The latest version of this connector uses employeeId (Medewerkernummer) as the ExternalId instead of personId (Persoonsnummer). **This can be a breaking change when updating from a previous version. Make sure to validate this!** |
+
+
 | :information_source: Information |
 |:---------------------------|
 | This repository contains the connector and configuration code only. The implementer is responsible to acquire the connection details such as username, password, certificate, etc. You might even need to sign a contract or agreement with the supplier before implementing this connector. Please contact the client's application manager to coordinate the connector requirements.       |
-<br />
+
 <p align="center">
   <img src="https://www.tools4ever.nl/connector-logos/afas-logo.png">
 </p>