Adds ml-cpp release notes (#137178)

Author: kosabogi

docs/release-notes/index.md

@@ -314,6 +314,9 @@ Machine Learning:
 * Track inference deployments [#131442](https://github.com/elastic/elasticsearch/pull/131442)
 * [ML] Add Azure AI Rerank support to the Inference Plugin [#129848](https://github.com/elastic/elasticsearch/pull/129848)
 * [ML] Add IBM watsonx Completion and Chat Completion support to the Inference Plugin [#129146](https://github.com/elastic/elasticsearch/pull/129146)
+* Update the PyTorch library to version 2.7.1 [#2863](https://github.com/elastic/ml-cpp/pull/2863)
+* Report the actual memory usage of the autodetect process [#2846](https://github.com/elastic/ml-cpp/pull/2846)
+* Improve adherence to memory limits for the bucket gatherer [#2848](https://github.com/elastic/ml-cpp/pull/2848)
 
 Mapping:
 * Add new `pattern_text` field mapper in tech preview [#135370](https://github.com/elastic/elasticsearch/pull/135370)