Document reproducible downstream Rivet installs

[turinglambdaai]

Summary

• standardize downstream hold-backs on a tag-pinned Git package source
• pin the Linux setup action and installed package to the same revision
• explain why the package install must run after the minimal embeddable runtime setup
• keep the English and Chinese guides aligned and regression-test the copy-paste contract

Validation

• raco test tests/documentation.rkt (163 tests passed)
• verified tag v0.7.0 contains both the root multi-collection package and setup action

Closes #213
Closes #214