Add Agents Shipgate to MCP resources

[pengfei-threemoonslab]

This adds Agents Shipgate to the additional MCP resources list.

Why:

• Agents Shipgate is a static release-readiness scanner for AI agent tool surfaces.
• MCP exports are one of its supported inputs, alongside OpenAPI specs and agent framework artifacts.
• This is a docs-only resource entry; it does not add CI or change any reference server implementation.

Trust model:

• No agent execution.
• No LLM calls.
• No tool calls.
• No MCP server connections.
• No scanner network calls.
• No telemetry.

I kept this intentionally small and placed it near related MCP discovery/security/scanning resources.