chore: Added image for device authorization flow

Added an image to illustrate the device authorization flow.

Author: unatasha8

docs/oauth2-oidc/device-authorization.mdx

@@ -24,6 +24,8 @@ Here is the high-level overview for the device authorization grant flow:
 1. In the meantime, the device polls the authorization server. Once the user authenticates and grants access, the authenicaton server 
    sends an access token to the device, which is used to access the protected resource.
 
+![Device authorization flow](/_static/deviceAuthFlow.png)
+
 ### Step 1: Device requests authorization
 
 The user attempts to log in through the limited input device. The device sends a POST request to the authorization server to initiate