Update README.md

Co-authored-by: Robert Pająk <[email protected]>

Author: carlosalberto

README.md

@@ -3,8 +3,10 @@
 [![Slack chat][slack-image]][slack-url]
 [![Build Status][circleci-image]][circleci-url]
 
-**:warning: OTEPs have been moved to the [Specification](https://github.com/open-telemetry/opentelemetry-specification/tree/main/oteps/)
-repository. This repository has been preserved for reference purposes. Please otherwise refer to the Specification.**
+> [!WARNING]  
+> OTEPs have been moved to the [Specification](https://github.com/open-telemetry/opentelemetry-specification/tree/main/oteps/)
+> repository. This repository has been preserved for reference purposes.
+> Please otherwise refer to the Specification.
 
 ## Evolving OpenTelemetry at the speed of Markdown