docs: fix Helm values file path (#146)

Fixed typo in instructions

Author: pioorg

.github/README.md

@@ -46,7 +46,7 @@ Additionally, the OpenTelemetry Contrib collector has also been changed to the [
 - Follow the [EDOT Quick Start Guide](https://elastic.github.io/opentelemetry/quickstart/) for Kubernetes and your specific Elastic deployment to install the EDOT OpenTelemetry collector.
 - Deploy the Elastic OpenTelemetry Demo using the following command.
   ```
-  helm install my-otel-demo open-telemetry/opentelemetry-demo -f kubernetes/elastic-helm/demo.yaml
+  helm install my-otel-demo open-telemetry/opentelemetry-demo -f kubernetes/elastic-helm/demo.yml
   ```
 
 #### Kubernetes architecture diagram