chore(cursor): update mcp example to use GitHub

[matifali]

Description

Uses a better example.

Type of Change

• New module
• Bug fix
• Feature/enhancement
• Documentation
• Other

Module Information

Path: registry/coder/modules/cursor
New version: v1.3.1
Breaking change: [ ] Yes [x] No

Testing & Validation

• Tests pass (bun test)
• Code formatted (bun run fmt)
• Changes tested locally

[Copilot]

Pull Request Overview

This pull request updates the Cursor module documentation to version 1.3.1 and replaces the MCP (Model Context Protocol) example configuration from using a local Coder server to using the GitHub MCP server with external authentication.

• Updates module version references from 1.3.0 to 1.3.1
• Replaces Coder MCP server example with GitHub MCP server configuration
• Adds documentation explaining GitHub external authentication setup

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