Fix wording in README.md

Author: jbern0rd

README.md

@@ -38,7 +38,7 @@ To run properly, the iExec Blockchain Adapter API requires:
 
 ## Health checks
 
-An health endpoint (`/actuator/health`) is enabled by default and can be accessed on the **IEXEC_BLOCKCHAIN_ADAPTER_API_PORT**.
+A health endpoint (`/actuator/health`) is enabled by default and can be accessed on the **IEXEC_BLOCKCHAIN_ADAPTER_API_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](docker/Dockerfile) at the moment.