Add doc on SFX_API_URL envvar for docker deployments
@@ -58,6 +58,7 @@ set the following environment variables on the agent container:
| --------- | -------- | ----------- |
| `SFX_ACCESS_TOKEN` | **yes** | The SignalFx API access token. |
| `SFX_INGEST_URL` | no | Often used in conjunction with the [SignalFx Metric Proxy](https://github.com/signalfx/metricproxy) to specify a different target URL for datapoints and events. If not specified, this defaults to the global SignalFx ingest server. |
+| `SFX_API_URL` | no | If you are operating in a different SignalFx realm, this value will need to be set to the SignalFx API server URL in your realm. |
The supplied configuration will also load any additional yaml files found in `/etc/signalfx/monitors/` as
part of the `monitors` list in the agent config like so:
