doc: Add Principal+ Engineering Demo to Engineering Communications

- **Principal+ Engineering Demo**: this call is an opportunity for sync discussions between
  Principal+ ICs across the Engineering Division to highlight current ongoing efforts underway in the groups they support.
  - Focuses for the call include:
    - Technical roadmap planning: dependencies, cross-departmental upstream requirements,
      opportunities for downstream improvements based on current projects. Future initiatives.
    - Opportunities for cross-department alignment, reuse of tooling, modules, processes,
      standards, technology, documentation.
    - Discussions on improving the career development resources for Engineering ICs at all levels
  - All team members are welcome to join the call,
    but the emphasis is on Principal+ ICs in the Engineering Division to present
    and discuss the work they’re focused on, the problems they’re experiencing,
    and solutions they’re considering.