doc: Added Upsonic Framework as example MCP cient

[onuratakan]

Hi, we are an open source framework for AI Agents (6.8K Star). We also integrated with MCP months ago.

Motivation and Context

We love to use MCP's in agents via Upsonic so we also thing people will love.

How Has This Been Tested?

We tested and our customers/users are using mcp servers over upsonic.

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 Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

No