[Internal]: Add known issue to 8.17.x

[milanage]

Description

Due to a known issue, we have disabled/blocked certain upgrade path on ECH. See the following KBs for details:

https://support.elastic.dev/knowledge/view/e87d76a5
https://support.elastic.dev/knowledge/view/7c3ad709

To be specific, the following path are disabled:

* -> 8.17.*                    # 1
8.17.* -> 8.18.[0-7]           # 2
8.17.* -> 8.19.[0,1,2,4]       # 3, # 4

While we have KBs but it's not easy for people, especially the customers, to find out this information if they did not know there is such thing. (due to the nature of KB - you need to know the keyword to find the information).

This has already caused customer frictions as customers wanted to upgrade to 8.17.x but were blocked unexpectedly.

It'll make more sense to add this information to the release notes as Known issues under 8.17.x versions.

Resources

elastic/kibana#210386
elastic/elasticsearch#133080
elastic/elasticsearch#135845
elastic/kibana#202891

Which documentation set does this change impact?

Elastic Cloud Hosted only

Feature differences

n/a

What release is this request related to?

8.17

Serverless release

n/a

Collaboration model

The documentation team

Point of contact.

Main contact: @

Stakeholders: