Minor adaption in contibute docu

docs/developer/contribute.md

@@ -19,7 +19,7 @@ Awesome! :sunglasses: Please make sure to read our *style guides* first:
 This is how you can actually make a difference:
 
 <figure markdown>
-  ![merge-request](assets/images/merge-request.jpg){width="500"}
+  ![merge-request](../assets/images/merge-request.jpg){width="500"}
   <figcaption>Merge request workflow</figcaption>
 </figure>