enhance readme

README.md

@@ -1,8 +1,21 @@
-# cumulocity-webrtc-webcam-plugin
+# Cumulocity WebRTC Webcam Plugin
 
-A plugin that allows to access the webcam of compatible cumulocity devices via webrtc
+A plugin that allows to access the webcam of compatible Cumulocity devices via [WebRTC](https://en.wikipedia.org/wiki/WebRTC).
+WebRTC allows to create a peer-to-peer connection between the Cumulocity device and the browser to stream the video.
+Because of that the video traffic does not have to go through another server or e.g. Cumulocity, which saves bandwith and costs.
 
-Have a look at the [cumulocity-electron-agent](https://github.com/SoftwareAG/cumulocity-electron-agent) for a sample implementation supporting this feature.
+![](images/webcam.png)
+
+The Webcam plugin adds a Webcam tab to compatible devices in the app you install it to. You can e.g. install it to the `Devicemanagement` or `Cockpit` application.
+
+The plugin uses by default some [STUN servers](https://de.wikipedia.org/wiki/Session_Traversal_Utilities_for_NAT) by Google to find the public IP addresses of the peer in order to establish the peer-to-peer connection. You can configure a different set of [ICE servers](https://en.wikipedia.org/wiki/Interactive_Connectivity_Establishment) (STUN or TURN) via the configuration plugin included in the package.
+
+Depending on the firewall setup beteen the two peers it might happen that a peer-to-peer connection can not be established.
+In that case a third party [TURN server](https://en.wikipedia.org/wiki/Traversal_Using_Relays_around_NAT) is required, where the video traffic passes through. You can host such a server on your own with e.g. [Coturn](https://github.com/coturn/coturn).
+
+Have a look at the [cumulocity-electron-agent](https://github.com/SoftwareAG/cumulocity-electron-agent) for a sample device agent implementation supporting this feature.
+
+Please note that this plugin will store **possible sensitive information** in form of e.g. **external and internal IP addresses** in Cumulocity operations in order to establish the peer-to-peer connection. A possible future solution to this could be to establish a websocket connection between the device and browser via a microservice to exchange those details without storing them in Cumulocity.
 
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