[JasonYeYuhe]

Summary

This PR adds a complete 1:1 Simplified Chinese translation (README.zh.md) of the main documentation and a PyPI-safe language switcher at the top of README.md to improve accessibility for Chinese-speaking machine learning researchers and developers.

Changes

• Added README.zh.md: Complete, natural Simplified Chinese translation of README.md, covering:
  • Introduction to Sonnet's snt.Module abstraction and unopinionated design philosophy
  • Getting started examples (Colab notebooks), installation, and built-in module usage (snt.Sequential, variables, trainable_variables)
  • Custom module creation by subclassing snt.Module and lazy parameter initialization with @snt.once
  • Serialization via TensorFlow Checkpointing (tf.train.Checkpoint) and TensorFlow SavedModel (tf.saved_model)
  • Distributed training with snt.distribute
• Updated README.md: Added a language navigation link (English · 简体中文) using an absolute GitHub URL (https://github.com/google-deepmind/sonnet/blob/v2/README.zh.md) so links work both on GitHub and on the PyPI dm-sonnet package page.
• Formatting & Fidelity: Preserved all code blocks, outputs, and external links 1:1.

Maintenance Commitment

I am happy to help maintain and sync README.zh.md whenever upstream documentation updates.