Update searchable snapshot to clarify

[kunisen]

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Update searchable snapshot to clarify it's not a backup of index data and deleting it will result in permanent data loss.

It's a follow up of #108451

[github-actions]

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[elasticsearchmachine]

@kunisen please enable the option "Allow edits and access to secrets by maintainers" on your PR. For more information, see the documentation.

[elasticsearchmachine]

Pinging @elastic/es-docs (Team:Docs)

[elasticsearchmachine]

Pinging @elastic/es-distributed (Team:Distributed)

[geekpete]

LGTM

[DaveCTurner]

IME it doesn't work very well to start sections with WARNING admonitions like this. Maybe one is ok, but then we add another, and another, and it ends up pushing the actual content of the section out of view.

Also, this warning is kind of confusing (what does it have to do with frozen/cold data?) and also kind of ambiguous (deleting the searchable snapshot index does not cause permanent data loss, it's only deleting the underlying snapshot while it's still mounted that causes problems).

Instead, maybe we should make this whole section into a WARNING, and add some more detail to each of the bullet points in the list about the consequences of ignoring the advice.

[kunisen]

Thank you @DaveCTurner so much for the quick and detailed guidance!
I didn't want to break the whole text so I only added a piece of warning, but indeed as you said, it's good to make the whole section a warning to bring the best awareness.

We are good with this change. If you don't mind, may I also ask your help to see if we can merge this PR, or if you can kindly forward this to doc team for doc-related reviews? 🙏

Thanks again!

[DaveCTurner]

LGTM

[kunisen]

thanks!
sorry forgot to add backport label.