Update README.md to reflect the new MariaDB official MCP server implementation.

[mariadb-RyanKillea]

Add official MariaDB MCP server implementation to documentation.

Description

MariaDB now has an official MCP server implementation that they are supporting, update the documentation to point to it.

Motivation and Context

Reflects the availability of a new official MCP server supported by MariaDB.

How Has This Been Tested?

N/A

Breaking Changes

None

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)
• [x ] 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

[olaservo]

Thanks for your contribution to the servers list. This has been merged in this combined PR: #2264

This is a new process we're trying out, so if you see any issues feel free to re-open the PR and tag me.