fix broken links in the Cargo book

Author: yegeunyang

src/doc/src/guide/build-cache.md

@@ -11,5 +11,5 @@ develop Rust packages.
 * [Cargo.toml vs Cargo.lock](cargo-toml-vs-cargo-lock.md)
 * [Tests](tests.md)
 * [Continuous Integration](continuous-integration.md)
+* [Publishing on crates.io](../reference/publishing.md)
 * [Cargo Home](cargo-home.md)
-* [Build Cache](build-cache.md)