Add overview diagram

Author: phwissmann

assets/img/documentation/dev/components.drawio.png

@@ -7,9 +7,14 @@ permalink: /documentation/dev/overview
 <!-- Show the current active documentation page -->
 {% include documentationStepper/stepper.html %}
 
-## Overview
+## High-level Overview
 
-In this section of the website you will find the documentation for the development of the OpenEM components.
+The following diagram shows the components involved in OpenEM and a (simplified) view of typical interactions between them.
+
+For simplicity, interactions regarding authentication flow are omitted. Please refer to the [Ingstor](https://github.com/SwissOpenEM/Ingestor) for a detailed description.
+
+![OpenEM Components](/assets/img/documentation/dev/components.drawio.png)
+*Green: Newly developed components; Blue: Modified existing components; Grey: Newly deployed third-party components; Orange: External components*
 
 ### External links