[8.15] Host isolation exceptions and VPN communication (backport #5579)…

… (#5632)

* Host isolation exceptions and VPN communication (#5579)

* Add to admonition [ESS]

* Add to admonition [serverless]

* Add back accidentally deleted line

(cherry picked from commit 3886a21)

# Conflicts:
#	docs/serverless/edr-manage/host-isolation-exceptions.mdx

* Delete docs/serverless directory and its contents

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Co-authored-by: Joe Peeples <[email protected]>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

docs/management/admin/host-isolation-exceptions.asciidoc

@@ -12,7 +12,12 @@ Host isolation exceptions support IPv4 addresses, with optional classless inter-
 You must have the *Host Isolation Exceptions* <<endpoint-management-req,privilege>> to access this feature.
 --
 
-IMPORTANT: Each host isolation exception IP address should be a highly trusted and secure location since you're allowing it to communicate with hosts that have been isolated to prevent a potential threat from spreading.
+[IMPORTANT]
+====
+* Each host isolation exception IP address should be a highly trusted and secure location since you're allowing it to communicate with hosts that have been isolated to prevent a potential threat from spreading.
+
+* If your hosts depend on VPNs for network communication, you should also set up host isolation exceptions for those VPN servers' IP addresses.
+====
 
 Host isolation is a https://www.elastic.co/pricing[Platinum or Enterprise subscription] feature. By default, a host isolation exception is recognized globally across all hosts running {elastic-defend}. You can also assign a host isolation exception to a specific {elastic-defend} integration policy, affecting only the hosts assigned to that policy.