Add Chinese translation for Deep Reinforcement Learning Course

[AmadeusGB]

Description

This PR adds Chinese translations for the Deep Reinforcement Learning Course materials. The translations cover all course units including core content, bonus units, and communication materials.

Changes

• Translated all course content in the units/cn directory
• Maintained consistent terminology across all translated files
• Preserved original formatting, code blocks, and image references
• Ensured mathematical formulas render correctly

Testing

• Verified all translated MDX files render properly
• Checked mathematical expressions for correct display
• Confirmed all links and references work in the translated version
• Validated consistency of technical terminology throughout the course

Additional Notes

The translation aims to make this valuable Deep RL content accessible to Chinese-speaking learners while maintaining the technical accuracy and educational quality of the original materials.