add connectors release notes 9.1.5 (#135921)

Author: charlotte-hoblik

docs/reference/search-connectors/release-notes.md

@@ -13,6 +13,13 @@ If you are an Enterprise Search user and want to upgrade to Elastic 9.0, refer t
 It includes detailed steps, tooling, and resources to help you transition to supported alternatives in 9.x, such as Elasticsearch, the Open Web Crawler, and self-managed connectors.
 :::
 
+## 9.1.5 [connectors-9.1.5-release-notes]
+
+### Features and enhancements [connectors-9.1.5-features-enhancements]
+* Refactored pagination from OFFSET-based to keyset (primary-key) pagination in the MySQL connector. This delivers 3×+ faster syncs on large tables and modest gains on smaller ones. [#3719](https://github.com/elastic/connectors/pull/3719).
+
+* Updated the Jira connector to use the new `/rest/api/3/search/jql` endpoint, ensuring compatibility with Jira’s latest API. [#3710](https://github.com/elastic/connectors/pull/3710).
+
 ## 9.1.4 [connectors-9.1.4-release-notes]
 
 ### Features and enhancements [connectors-9.1.4-features-enhancements]