docs: add uml diagram of schema

Author: rmfranken

README.md

@@ -4,6 +4,9 @@ This repo contains the SHACL shapes and the IP Ontology used for:
 
 - Fair Calculation
 
+## Basic Schema Diagram (UML)
+
+![ontology_combined](https://github.com/user-attachments/assets/6b8cafae-9e2c-4dbc-a3e0-f1915f343d81)
 
 ## Changelog
 
@@ -17,3 +20,4 @@ This repo contains the SHACL shapes and the IP Ontology used for:
 - **v0.8**: Update FAIR levels, contributors+producers become authors. First+Last name becomes schema:name.
 - **v0.9**: Support for runnable examples, dicom dataset properties, spelling mistakes.
 - **v1.0**: Update enumerations modelling to use skos for taxonomy, expand meta-shacl shapes, Various CI improvements, removal of unused properties and shapes.
+