Initial model office: Oscalate Systems

[pjavan]

This pull request introduces a comprehensive documentation and example structure for the OSCAL Foundation Pattern Library, focusing on the "Summit" model office example. It adds detailed README files for the root and each OSCAL model directory, and includes a full example OSCAL profile (oscalate_systems_moderate_profile.json). The goal is to provide the community with high-quality, realistic OSCAL artifacts and clear guidance on their structure and relationships.

Key changes include:

Project-wide Documentation and Structure:

• Enhanced the main README.md to introduce the OSCAL Foundation Pattern Library, explain its purpose, describe the OSCAL Foundation, outline the seven OSCAL models, and clarify repository structure and contribution guidelines.
• Added a detailed summit/README.md describing the Summit model office example, its architecture, the included OSCAL models, their relationships, and file formats.

Model-specific Documentation:

• Added README files for each OSCAL model directory under summit/, each explaining the model's purpose, what artifacts belong in the directory, key concepts, and links to official OSCAL documentation:
  • catalog/README.md for Catalog
  • profile/README.md for Profile
  • component-definition/README.md for Component Definition
  • assessment-plan/README.md for Assessment Plan
  • assessment-results/README.md for Assessment Results
  • poam/README.md for Plan of Action and Milestones (POA&M)

Example OSCAL Artifacts:

• Added a complete example OSCAL Profile (oscalate_systems_moderate_profile.json) under summit/profile/, representing a moderate baseline with detailed metadata, imports, and references to the NIST SP 800-53 Rev 5 catalog.