README modification - how to register new MCP tools

To add a new tool:

1. Define Pydantic models for request, response data schema validation.

2. Define the tool in `tools/your_tool.py`.

3. Decorate it with the `@app.tool()` decorator in `app.py`:

3. Registers a tool in `app.py`:

   ```python

    from MCP_dummy_Camara.tools.your_tool import new_function

   app.tool()(new_function)

    app.tool()(new_function)  # registers it as a tool

   ```

4. Add corresponding models and JSON templates if needed.