DOC-12465 non avx2 processor deprecation 7.6 (#3703)

* Added deprecation section to 7.6.3 release notes for the future AVX2 requirements.

* Rewording.

* Fixing anchor

Author: ggray-cb

modules/release-notes/partials/docs-server-7.6.3-release-note.adoc

@@ -4,6 +4,13 @@ Couchbase Server 7.6.3 was released in September 2024. This maintenance release
 
 For detailed information on new features and enhancements, please see xref:introduction:whats-new.adoc[].
 
+[#deprecated-7-6-3]
+=== Deprecated Platforms
+
+The use of x86 processors that do not support Advanced Vector Extensions 2 (AVX2) is deprecated in version 7.6.3. 
+Future versions of Vector Search will rely on these instructions to improve performance.
+These instructions are available in most Intel processors produced since 2013 and AMD processors produced since 2015. 
+
 [#fixed-issues-763]
 === Fixed Issues