DOC-12540 AVX2 requirements

[ggray-cb]

This updates the documentation to state that Couchbase Server on x86 now requires AVX2 instructions.

Preview URL:
https://preview.docs-test.couchbase.com/docs-server-DOC-12540_AVX_requirements

You will need the Docs Team credentials on Confluence.

Main changes, with links to preview:

• Removed non-AVX2 x86 processor deprecation notice from Release Notes page (AVX2 is now required, not derepcated). Note that the release note for the JIRA ticket for preventing Couchbase Server from starting without AVX2 is not finished yet, so it does not appear in this preview.
• In System Resource Requirements:
  • Removed "deprecated" and state that AVX2 is required on x86 platforms.
  • Removed language that tied the requirement to vector indexes at PM's request.
  • Simplified the presentation by taking information spread across a table, admonition, and several paragraphs and put it into one table per platform. Something to take particular note of: we didn't actually specify requirements for using XDCR on the ARM platform before. I assume we have similar requirements to the x86 platform, so I added that entry in. If that's wrong, please let me know.

[Copilot]

Pull Request Overview

This PR updates the documentation to reflect that Couchbase Server on x86 platforms now requires AVX2 instructions instead of just deprecating non-AVX2 processors. The change moves from a deprecation notice to a hard requirement for AVX2 support.

Key changes:

• Removes the deprecation notice for non-AVX2 x86 processors from release notes
• Updates system requirements to make AVX2 mandatory for x86 platforms
• Restructures the processor requirements documentation with clearer tables and consolidated information

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
modules/release-notes/pages/relnotes.adoc	Removes deprecated platforms section that warned about AVX2 requirement
modules/install/pages/pre-install.adoc	Updates system requirements to make AVX2 mandatory and restructures documentation with clearer tables

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}