Fix bad copy-paste mistake

[gagbo]

Description

Fixes issue #85

Checklist

• [ ] The CHANGELOG is updated.
• [x] The open-telemetry example in repository works fine:
  • the docker compose file is valid
  • the application compiles and run
  • alerts are getting triggered in Prometheus
• [x] The prometheus example in repository works fine:
  • the docker compose file is valid
  • the application compiles and run
  • alerts are getting triggered in Prometheus
  • exemplars are accessible on the graph