Add docs for the Recorded Future fileset

[nastasha-solomon]

The Threat Intel module topic need to be updated to reflect that an integration for the Recorded Future threat feed is now available. In addition, I'll need to insert a new section for the Recorded Future fileset configuration details.

Related issues/PRs:

• Add integration for Recorded Future threat intel integrations#2757
• Bump github.com/elastic/elastic-package from 0.43.0 to 0.44.0 integrations#2916
• Add event.created field mapping to TI packages integrations#3042

cc: @dedemorton @adriansr

[elasticmachine]

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

[nastasha-solomon]

I'll be working with @dedemorton to make sure the CI checks pass on the PR I'll eventually be opening.

[dedemorton]

So based on Adrian's PR here, it looks like we can close this issue because the Recorded Future fileset does not exist in the Filebeat module.