Add official Couchbase MCP server

[nithishr]

Description

This PR adds the official Couchbase MCP server to the list of official integrations. The Couchbase MCP server allows users to explore and query the data stored in Couchbase clusters (both Capella Cloud & self-managed).

Motivation and Context

This addition allows users to discover the integration.

How Has This Been Tested?

The MCP server has been tested against multiple MCP clients, including Claude Desktop, Cursor & Windsurf.

Breaking Changes

No breaking changes. PR is only updating the README file.

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/Couchbase-Ecosystem/mcp-server-couchbase