docs(tracer): add note on why X-Ray SDK over ADOT closes #1675

Author: heitorlessa

docs/core/tracer.md

@@ -19,6 +19,8 @@ Tracer is an opinionated thin wrapper for [AWS X-Ray Python SDK](https://github.
 ???+ tip
     All examples shared in this documentation are available within the [project repository](https://github.com/awslabs/aws-lambda-powertools-python/tree/develop/examples){target="_blank"}.
 
+!!! note "Tracer relies on AWS X-Ray SDK over [OpenTelememetry Distro (ADOT)](https://aws-otel.github.io/docs/getting-started/lambda){target="_blank"} for optimal cold start (lower latency)."
+
 ### Install
 
 !!! info "This is not necessary if you're installing Powertools via [Lambda Layer/SAR](../index.md#lambda-layer){target="_blank"}"