Update index.md (#1832)

Add EDOT to the Reference index.

Author: theletterf

reference/index.md

@@ -38,6 +38,12 @@ Customize your Elastic Stack setup with our configuration reference guides. Expl
 
 **Learn more in [Elasticsearch and index management](elasticsearch://reference/elasticsearch/index.md)**
 
+## Elastic Distributions of OpenTelemetry (EDOT)
+
+Elastic Distributions of OpenTelemetry (EDOT) is an open-source ecosystem of OpenTelemetry distributions tailored to Elastic. They include a customized OpenTelemetry Collector and several OpenTelemetry Language SDKs.
+
+**Learn more in [Elastic Distributions of OpenTelemetry](opentelemetry://reference/index.md)**
+
 ## Ingestion tools
 
 Streamline data ingestion with tools like Fleet and Elastic Agent, APM, and Beats. Explore processor references and Logstash plugins to efficiently manage your data flow.