Update README.md: added link to spec and more info about CLA

Signed-off-by: Jacobus Geluk <jacobus.geluk@ekgf.org>

README.md

@@ -6,6 +6,10 @@ Artifacts of the EKGF Data Product Workgroup
 - [Ontologies](ontology/README.md)
 - [Concepts](concept/README.md)
 
-## Contribution Licence Agreement
+The specification is generated by Respec and (temporarily) published here: https://ekgf.github.io/data-product-spec/dprod
+
+## Contributor Licence Agreement (CLA)
+
+We're using the CLA assistant service to collect CLA signatures of all contributors.
 
 [![CLA assistant](https://cla-assistant.io/readme/badge/EKGF/data-product)](https://cla-assistant.io/EKGF/data-product)