Add COMMUNITY page and MCP cookbook docs

Add new documentation: a generated COMMUNITY.html page for the site and two cookbook sources describing MCP support: docs/cookbook/src/crates/rustapi_mcp.md (overview of the rustapi-mcp crate, features, security model, transport and roadmap) and docs/cookbook/src/recipes/mcp_integration.md (detailed recipe with examples, usage, dependency snippet, invocation modes, permission scoping, tool discovery, and operational notes). These files document how to expose tagged endpoints as discoverable MCP tools, configure McpServer/McpConfig, and run RustAPI alongside an MCP server (including in-process dispatch and security controls).

Author: Tuntii