Add documentation for $resource-count operation

[Copilot]

This PR adds comprehensive documentation for the new $resource-count operation introduced in FirelyTeam/Vonk#2624.

Overview

The $resource-count operation is a new system-level administration API that provides statistics about the number of resources stored in the Firely Server database, grouped by resource type. This operation is useful for monitoring, analytics, and understanding the distribution of data in your FHIR server.

What's Added

New Documentation File

• Created /features_and_tools/custom_operations/resource-count.rst with comprehensive documentation
• Added the operation to the custom operations index and table of contents

Documentation Content

• Operation Details: Complete API specification including endpoint, request/response format
• Configuration: Default settings and configuration options
• Repository Support: Coverage for all database backends (SQL Server, SQLite, MongoDB)
• Security: Access control and network protection information
• Performance: Considerations for large datasets and optimization details
• Use Cases: Practical applications including monitoring, analytics, and debugging
• Examples: Complete request/response examples including cURL usage
• Limitations: Clear documentation of current constraints

Key Features Documented

• Endpoint: GET /administration/$resource-count
• Response Format: JSON object with resource types as keys and counts as values
• Filtering Logic: Only counts current, non-contained, non-deleted resources
• Example Response:

  {
      "Patient": 1250,
      "Observation": 4892,
      "Encounter": 892,
      "Practitioner": 45,
      "Organization": 12,
      "Medication": 234
  }

Screenshot

The documentation has been successfully integrated into the existing Firely Server documentation structure:

Testing

• Documentation builds successfully with Sphinx
• Proper navigation and cross-references work correctly
• Follows established documentation patterns and style guidelines
• All links and references are valid

This documentation provides users with everything they need to understand and use the new $resource-count operation effectively.

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