docs(model-converter): add graphical conversion guide

[liangzhuohua]

Summary

• add Chinese and English documentation for Maix Converter Platform
• explain how to convert YOLO models through the Web interface
• document Python and Docker environment setup
• describe model inputs, calibration datasets, conversion parameters, output files, logs, and common issues
• add the new guide to the Chinese and English sidebars
• add the existing ONNX output-node guide to the English sidebar

Motivation

The existing MaixCAM and MaixCAM2 model-conversion guides require users to run many commands and configure the
conversion toolchains manually.

Maix Converter Platform provides a Web interface that automates model export, output-node processing, quantization,
MUD generation, and result packaging. This guide makes the workflow easier to follow, especially for beginners.

Current Support

• MaixCAM
• MaixCAM Pro
• MaixCAM2
• YOLO26 Detect
• YOLO11 Detect
• YOLOv8 Detect
• .pt and .onnx input models

Related Project

• https://github.com/sipeed/maix_converter_platform

Testing

• successfully built the Chinese and English documentation with teedoc build
• checked Markdown code blocks and relative document links