SAST documentation: latest template is referenced in docs

Documentation 📈

Our documentation does not include information about the latest template.
This template has features that are unavailable in the regular template (specifically, MR pipeline support).

Add a heading to the SAST docs page that covers the current offering available with the latest template, while clarifying that it is less stable.

Success Criteria

• Submit a documentation update MR
• Pass groupstatic analysis review
• Pass Technical Writing review
• Merge the update
• Update groupstatic analysis OKR