### What problem does this PR solve?
Add tips for installing Chinse fonts under code sandbox. Otherwise,
`matplotlib `won't render Chinese correctly.
<img width="2082" height="1186" alt="sales_analysis"
src="https://github.com/user-attachments/assets/57e675ab-1e92-4662-9aeb-ad72a6121eb5"
/>
### Type of change
- [x] Documentation Update
