docs: add Matrix MCP server

[mjknowles]

Description

This MR adds a link to my Matrix MCP server that I've built. Functionality right now is limited to read-only type functionality but I will keep expanding upon it. Users can utilize this MCP server to query and interact with the Matrix homeservers via natural language utilizing their favorite MCP client tool(s).

Motivation and Context

This MCP server helps me keep up with the activity on my Matrix server(s) by leveraging natural language and the power of LLMs to summarize and query my chat data.

How Has This Been Tested?

For this specific PR, I have previewed the markdown and LGTM.

For functionality of the actual MCP server, I run my own Matrix homeserver locally and pointed my MCP at it. The MCP server has all the configuration options needed to integrate with the Matrix server's IdP for authentication.

I used Claude Code to install all the tools in the matrix-mcp-server project and then used it to run a full gamut of tests against my own live data.

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

• This MCP server utilizes HTTP streaming transport
• The README includes configuration examples for both Claude Code and vscode.

[mjknowles]

Note - I believe this would be classified as a "community server". I have no affiliation with matrix.org. Just a user of the software.