docs: options compared to wg configuration file

docs/usage.md

@@ -11,3 +11,31 @@ After setting the environment options in `wghttp.service`, run:
 systemctl --user daemon-reload
 systemctl --user enable --now wghttp
 ```
+
+## Options compared to WireGuard configuration file
+
+For connecting as a client to a VPN gateway, you might have:
+
+```ini
+[Interface]
+Address = 10.200.100.8/24
+DNS = 10.200.100.1
+PrivateKey = oK56DE9Ue9zK76rAc8pBl6opph+1v36lm7cXXsQKrQM=
+
+[Peer]
+PublicKey = GtL7fZc/bLnqZldpVofMCD6hDjrK28SsdLxevJ+qtKU=
+AllowedIPs = 0.0.0.0/0
+Endpoint = demo.wireguard.com:51820
+```
+
+The above configuration is equal to:
+
+```bash
+wghttp \
+  --peer-endpoint=demo.wireguard.com:51820 \
+  --peer-key=GtL7fZc/bLnqZldpVofMCD6hDjrK28SsdLxevJ+qtKU= \
+  --private-key=oK56DE9Ue9zK76rAc8pBl6opph+1v36lm7cXXsQKrQM= \
+  --client-ip=10.200.100.8 \
+  --dns=10.200.100.1 \
+  --exit-mode=remote
+```