docs: Document Edge Proxy server.proxy_headers option

docs/docs/deployment/hosting/locally-edge-proxy.md

@@ -151,6 +151,27 @@ Optionally, specify the LRU cache size with `cache_max_size`. Defaults to 128.
 }
 ```
 
+### Server settings
+
+#### `server.proxy_headers`
+
+When set to `true`, the Edge Proxy will use the `X-Forwarded-For` and `X-Forwarded-Proto` HTTP headers to determine
+client IP addresses. This is useful if the Edge Proxy is running behind a reverse proxy, and you want the
+[access logs](#logging.override) to show the real IP addresses of your clients.
+
+By default, only the loopback address is trusted. This can be changed with the [`FORWARDED_ALLOW_IPS` environment
+variable](#environment-variables).
+
+```json
+"server": {
+  "proxy_headers": true
+}
+```
+
+```
+SERVER_PROXY_HEADERS=true
+```
+
 ### Logging
 
 #### `logging.log_level`
@@ -286,3 +307,5 @@ Some Edge Proxy settings can only be set using environment variables:
 - `HTTP_PROXY`, `HTTPS_PROXY`, `ALL_PROXY`, `NO_PROXY`: These variables let you configure an HTTP proxy that the
   Edge Proxy should use for all its outgoing HTTP requests.
   [Learn more](https://www.python-httpx.org/environment_variables)
+- `FORWARDED_ALLOW_IPS`: Which IPs to trust for determining client IP addresses when using the `proxy_headers` option.
+  For more details, see the [Uvicorn documentation](https://www.uvicorn.org/settings/#http).