[Internal]: 9.1 upgrade docs (ingest components)

[colleenmcginnis]

Description

🍷 Pairs well with #1685

We'll need to make sure all upgrade paths are correctly surfaced for 9.1 in the upgrade docs:

• The only way to upgrade to 9.0 will still be from 8.18 (and not 8.19)
• To upgrade to 9.1, you can be on either 9.0 or 8.19

The ingest docs team will own any content related to upgrading ingest components

Note: The admin docs team will cover orchestrator and cluster upgrade content and other pages will have co-ownership.

Resources

internal

upgrade paths info: https://support.elastic.dev/knowledge/view/31977c54

Which documentation set does this change impact?

Elastic On-Prem and Cloud (all)

Feature differences

TBD

What release is this request related to?

9.1

Serverless release

TBD

Collaboration model

The documentation team

Point of contact.

Main contact: TBD

Stakeholders: TBD

[colleenmcginnis]

All the links on the upgrade ingest components are still correct.