docs: Update README with diagram

Author: naji247

README.md

@@ -50,6 +50,9 @@ Use MCPcat for:
 - **Trace debugging** 🔍. See where your users are getting stuck, track and find when LLMs get confused by your API, and debug sessions across all deployments of your MCP server.
 - **Existing platform support** 📊. Get logging and tracing out of the box for your existing observability platforms (OpenTelemetry, Datadog, Sentry) — eliminating the tedious work of implementing telemetry yourself.
 
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+<img width="1274" height="770" alt="mcpcat-diagram" src="https://github.com/user-attachments/assets/2d75de19-5b69-4f8b-aea9-43161de5a2ba" />
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 ## Getting Started
 
 To get started with MCPcat, first create an account and obtain your project ID by signing up at [mcpcat.io](https://mcpcat.io). For detailed setup instructions visit our [documentation](https://docs.mcpcat.io).