[Docs] Increase vm.max_map_count suggested value

[shainaraskas]

We want to recommend a higher vm.max_map_count for Elasticsearch environments - additional context in issue

What issues does this PR fix?

Part of https://github.com/elastic/docs-content-internal/issues/592

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It looks like this PR modifies one or more .asciidoc files. These files are being migrated to Markdown, and any changes merged now will be lost. See the migration guide for details.

[shainaraskas]

this page does not exist in previous versions and should be redirected instead. opened an issue for that

https://github.com/elastic/docs-content-internal/issues/615