[8.10] [DOCS] Add cross-link for other encryption key settings (#165014) (#165034)

# Backport

This will backport the following commits from `main` to `8.10`:
- [[DOCS] Add cross-link for other encryption key settings
(#165014)](https://github.com/elastic/kibana/pull/165014)

<!--- Backport version: 8.9.7 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

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Add cross-link for other encryption key settings (#165014)\n\nProblem:
The [Configure security in
Kibana](https://www.elastic.co/guide/en/kibana/current/using-kibana-with-security.html)
docs page only covers the `xpack.security.encryptionKey` setting for
session encryption. Users may not know that encryption for Kibana's
reporting and saved objects features also require encryption
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Add cross-link for other encryption key settings (#165014)\n\nProblem:
The [Configure security in
Kibana](https://www.elastic.co/guide/en/kibana/current/using-kibana-with-security.html)
docs page only covers the `xpack.security.encryptionKey` setting for
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Add cross-link for other encryption key settings (#165014)\n\nProblem:
The [Configure security in
Kibana](https://www.elastic.co/guide/en/kibana/current/using-kibana-with-security.html)
docs page only covers the `xpack.security.encryptionKey` setting for
session encryption. Users may not know that encryption for Kibana's
reporting and saved objects features also require encryption
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Co-authored-by: James Rodewig <james.rodewig@elastic.co>

docs/user/security/securing-kibana.asciidoc

@@ -27,7 +27,7 @@ configure additional security settings and authentication.
 
 . Set the `xpack.security.encryptionKey` property in the `kibana.yml`
 configuration file. You can use any text string that is 32 characters or longer
-as the encryption key.
+as the encryption key. Refer to <<xpack-security-encryptionKey,`xpack.security.encryptionKey`>>.
 +
 --
 [source,yaml]
@@ -35,7 +35,10 @@ as the encryption key.
 xpack.security.encryptionKey: "something_at_least_32_characters"
 ----
 
-For more information, see <<security-settings-kb,Security settings in {kib}>>.
+{kib}'s reporting and saved objects features also have encryption key settings.
+Refer to <<xpack-reporting-encryptionKey,`xpack.reporting.encryptionKey`>> and
+<<xpack-encryptedSavedObjects-encryptionKey,`xpack.encryptedSavedObjects.encryptionKey`>>
+respectively.
 --
 
 . Optional: <<xpack-security-session-management,Configure {kib}'s session expiration settings>>.