Audit and update usages of "SaaS" (vs Self-Managed) in the docs

[conceptualshark]

Content, guides, etc, outside of the Self-Managed section should be installation-agnostic where applicable. The Self-Managed section should include installation, configuration, and deployment information, and the docs should not imply a separate product or product usage.

Problem: The term "SaaS" is used throughout the docs and is confusing as to what is or is not applicable to Self-Managed deployments.

Look at uses of "SaaS" throughout the docs, and:

1. Remove it where it is not describing a SaaS-only use or feature
2. Ensure the SaaS label is used where it should be
3. Create SM content (or issues) where it is missing to create a more comprehensive experience

Considerations

• All of the screenshots use the SaaS version of the product