Add link to mcp-arangodb-async server

[PCfVW]

Description

Add link to async Python ArangoDB Graph MCP server (33 tools, graph capabilities, strict Pydantic validation) in README.

Motivation and Context

The first ArangoDB MCP Server (ravenwits/mcp-server-arangodb) was implemented in TypeScript and did not provide direct access to ArangoDB graph capabilities. It offered backup functionality but lacked restore, conversion utilities, and other advanced features.
This pull request adds a link to an async-first Python MCP server that delivers 33 tools, full graph management and analytics capabilities, backup and restore functionality, content conversion (JSON, Markdown, YAML, Table), and strict Pydantic validation. This addition helps users discover a more feature-rich and robust MCP server solution for ArangoDB.

How Has This Been Tested?

The server was tested using both Augment Code (advanced testing) and Claude Desktop (basic testing).
Testing included a basic e-commerce scenario (which was not included in the README) and graphing of HDDL domains and problems, using resources from IPC 2020 domains.

Breaking Changes

No.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Protocol Documentation
• My changes follows MCP security best practices
• I have updated the server's README accordingly
• I have tested this with an LLM client
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have documented all environment variables and configuration options

Additional context

https://github.com/PCfVW/mcp-arangodb-async?tab=readme-ov-file#not-implemented-by-design