Add License link in README.md

Author: jbern0rd

README.md

@@ -35,3 +35,7 @@ You can configure the iExec Result Proxy with the following properties:
 A health endpoint (`/actuator/health`) is enabled by default and can be accessed on the **IEXEC_RESULT_PROXY_PORT**.
 This endpoint allows to define health checks in an orchestrator or a [compose file](https://github.com/compose-spec/compose-spec/blob/master/spec.md#healthcheck).
 No default strategy has been implemented in the [Dockerfile](Dockerfile) at the moment.
+
+## License
+
+This repository code is released under the [Apache License 2.0](LICENSE).