Update README.md

README.md

 # Large-Scale Metrology
 Schema for modeling a Large-Scale Metrology Device in SOIL
 
+![Overview](./media/LSM-System-Model.png)
+
 ## Viewing
 To view the schema, you can use any tool that supports the OpenAPI specification and open the bundled file at [public/openapi.yml](https://git-ce.rwth-aachen.de/wzl-mq-public/soil/schemas/large-scale-metrology/-/blob/76a54aeb9f4ee987ff056d53a4a6c3b32ad2aa7f/public/openapi.yml).