Add Mermaid diagram

README.md

@@ -1,6 +1,19 @@
 # iapc
 Alternative client and Go library for Google Cloud's Identity-Aware Proxy. This is based on an implementation in [gartnera/gcloud](https://github.com/gartnera/gcloud) and the official gcloud source code. It aims to expose more functionality and have better performance. It's worth mentioning that the IAP speaks a slightly modified version of the SSH Relay v4 protocol documented [here](https://chromium.googlesource.com/apps/libapps/+/HEAD/nassh/docs/relay-protocol.md#corp-relay-v4).
 
+```mermaid
+flowchart LR
+    subgraph Client
+        Client1[Client 1] --- IAPC
+        Client2[Client 2] --- IAPC
+    end
+    subgraph Google Cloud
+        IAPC -- WebSocket --> IAP(Identity-Aware Proxy)
+        IAP --- Instance
+        IAP --- HostIP["Host (requires BeyondCorp)"]
+    end
+```
+
 ## Usage
 The CLI needs to acquire Application Default Credentials (ADC) to authenticate with the proxy, so make sure you're logged in.