[DOC-12898]: Release note for 7.6.5

Resolved critical bugs in the Data, Query, and Search services to improve stability and functionality. Fixes include recovery log handling in Data Service, UDF execution with nested ARRAY constructs in Query Service, and index creation during rebalance in Search Service. Additionally, addressed upgrade-rebalance failures in the Search Service for version 7.6.5.

Clarify the release date as January 2025 and adjust phrasing for consistency in descriptions.

Previously, plans were not computed for indexes created if a rebalance stopped midway. This change ensures plan computation occurs even in such cases, improving system reliability.

modules/release-notes/pages/relnotes.adoc

@@ -3,6 +3,8 @@
 :description: Couchbase Server 7.6.x introduces multiple new features and fixes, as well as some deprecations and removals.
 :page-toclevels: 2
 
+include::partial$docs-server-7.6.5-release-note.adoc[]
+
 include::partial$docs-server-7.6.4-release-note.adoc[]
 
 include::partial$docs-server-7.6.3-release-note.adoc[]

modules/release-notes/partials/docs-server-7.6.5-release-note.adoc

@@ -0,0 +1,79 @@
+== Release 7.6.5 (February 2025)
+
+Couchbase Server 7.6.5 was released in January 2025.
+This maintenance release contains new features and fixes several known issues.
+
+For detailed information on new features and enhancements, see xref:introduction:whats-new.adoc[].
+
+[#fixed-issues-765]
+=== Fixed Issues
+
+This release contains the following fixes:
+
+==== Data Service
+
+[#table-fixed-issues-765-data-service,cols="10,40,40"]
+|===
+|Issue | Description | Resolution
+
+| https://jira.issues.couchbase.com/browse/MB-64742[MB-64742]
+| An issue in the plasma tracking stats flagged a stale recovery point in the recovery log as valid data.
+This made the log cleaning run slowly at a low mutation rate,
+and therefore, unable to trim the recovery point history effectively.
+At a higher mutation rate, the mutations alone could push the fragmentation ratio high enough to start the log cleaner,
+and therefore, was  able to trim rp history despite the issue with tracking stats.
+
+
+| We  mark the latest version of the recovery point that exists in both the recovery log and the data log.
+This effectively means that plasma will keep the recovery point history list to 1 in the recovery log.
+In addition,
+the plasma tracking stats are fixed such that it no longer treats the older recovery point as valid data in the recovery log.
+This allows the log cleaner to run even at a low mutation rate.
+
+
+|===
+
+==== Query Service
+
+[#table-fixed-issues-765-query-service,cols="10,40,40"]
+|===
+|Issue | Description | Resolution
+
+| https://jira.issues.couchbase.com/browse/MB-64684[MB-64684]
+a| If an inline user-defined function (UDF) includes a query with a nested **ARRAY** construct,
+and the innermost **ARRAY** construct refers to both:
+
+* a UDF argument, and
+* the binding variable of an outer **ARRAY** construct,
+
+Then the UDF creation or execution could fail.
+
+| Issue resolved
+
+|===
+
+
+==== Search Service
+
+[#table-fixed-issues-765-search-service,cols="10,40,40"]
+|===
+|Issue | Description | Resolution
+| https://jira.issues.couchbase.com/browse/MB-64652[MB-64652]
+a| An issue  in versioning can cause an online upgrade-rebalance operation
+to fail on account of a planning algorithm betterment change. 
+The bug will impact the failover-recovery online upgrade path as well.
+
+NOTE: This issue will only surface when an upgrade is attempted over a system with search indexes from `7.6.[0–3]` to `7.6.4`.
+
+
+| The issue has been resolved in version `7.6.5`. Our recommendation is to avoid this by moving directly to this version.
+
+| https://jira.issues.couchbase.com/browse/MB-64764[MB-64764]
+| If an index was created during rebalance,
+and the rebalance is stopped before plans are computed for that index,
+then no plans or partitions are created for the index until a subsequent rebalance is completed.
+| The corrected behavior ensures that plans are computed for indexes created during a rebalance, 
+even if the rebalance is stopped midway.
+
+|===
+