Add community Grafana Tempo mcp server

[scottlepp]

Description

Add Grafana Tempo MCP server to the community servers list in README.md

Server Details

• Server: Tempo

Motivation and Context

Allows querying spans and traces from Tempo.

How Has This Been Tested?

Tested from Claude Desktop.

The repo also has test scripts

Breaking Changes

No breaking changes.

Types of changes

• New feature (non-breaking change which adds functionality)
• 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

[olaservo]

Thanks for your contribution to the servers list. This has been merged in this combined PR: #2007

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.