DOCS-659 - Reorganize Cloud Infrastructure Security under "Logs for Security"

[jpipkin1]

Purpose of this pull request

This pull request renames the "Additional Security Features" article to "Logs for Security", and places the "Cloud Infrastructure for Security" section under it:
https://help.sumologic.com/docs/security/additional-security-features/

Select the type of change

• Minor Changes - Typos, formatting, slight revisions
• Update Content - Revisions, updating sections
• New Content - New features, sections, pages, tutorials
• Site and Tools - .clabot, version updates, maintenance, dependencies, new packages for the site (Docusaurus, Gatsby, React, etc.)

Ticket (if applicable)

DOCS-659

[kimsauce]

This was a complicated one - nice work, looks perfect.

[jpipkin1]

Thanks for reviewing it, @kimsauce!