fix README links

azure-monitor-events-extension/README.md

@@ -5,6 +5,11 @@ This distro automatically installs the following libraries:
 
 ### Additional documentation
 
-* [Azure Portal][https://portal.azure.com]
-* [Official Azure monitor docs][https://learn.microsoft.com/azure/azure-monitor/app/opentelemetry-enable?tabs=python]
-* [OpenTelemetry Python Official Docs][https://opentelemetry.io/docs/instrumentation/python/]
+* [Azure Portal][azure_portal]
+* [Official Azure monitor docs][azure_monitor_opentelemetry]
+* [OpenTelemetry Python Official Docs][ot_python_docs]
+
+<!-- LINKS -->
+[azure_portal]: https://portal.azure.com
+[azure_monitor_opentelemetry]: https://learn.microsoft.com/azure/azure-monitor/app/opentelemetry-enable?tabs=python
+[ot_python_docs]: https://opentelemetry.io/docs/instrumentation/python/