Update SIEM advanced settings

[benskelker]

Need to update SIEM settings documentation on the Kabana > Management > Advanced Settings page.

[gchaps]

@benskelker The page you want to edit is here:

https://www.elastic.co/guide/en/kibana/7.3/advanced-options.html

Add the content the same way it appears in the UI. So the SIEM section goes after the Search section.

[benskelker]

Reopening for 7.5 as UI text updated