Added 2.18.0 release notes. (#1718) (#1720)

* Added 2.18.0 release notes.



* Added 2.18.0 release notes.



* Added 2.18.0 release notes.



---------


(cherry picked from commit e1f05c9)

Signed-off-by: AWSHurneyt <[email protected]>
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: opensearch-trigger-bot[bot]

release-notes/opensearch-alerting.release-notes-2.18.0.0.md

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+## Version 2.18.0.0 2024-10-28
+Compatible with OpenSearch 2.18.0
+
+### Maintenance
+* Increment version to 2.18.0-SNAPSHOT. ([#1653](https://github.com/opensearch-project/alerting/pull/1653))
+
+### Refactoring
+* Adding Alerting Comments system indices and Security ITs ([#1659](https://github.com/opensearch-project/alerting/pull/1659))
+* add logging for remote monitor execution flows ([#1663](https://github.com/opensearch-project/alerting/pull/1663))
+* separate doc-level monitor query indices for externally defined monitors ([#1664](https://github.com/opensearch-project/alerting/pull/1664))
+* move deletion of query index before its creation ([#1668](https://github.com/opensearch-project/alerting/pull/1668))
+* create query index at the time of monitor creation ([#1674](https://github.com/opensearch-project/alerting/pull/1674))
+
+
+### Bug Fixes
+* delete query index only if put mappings throws an exception ([#1685](https://github.com/opensearch-project/alerting/pull/1685))
+* optimize bucket level monitor to resolve alias to query only those time-series indices that contain docs within timeframe of range query filter in search input ([#1701](https://github.com/opensearch-project/alerting/pull/1701))
+* fix number of shards of query index to 0 and auto expand replicas to 0-1 ([#1702](https://github.com/opensearch-project/alerting/pull/1702))
+
+### Documentation
+* Added 2.18.0 release notes. ([#1718](https://github.com/opensearch-project/alerting/pull/1718))