message: Fix broken link in Build Cache chapter.
diff: @@ -83,6 +83,7 @@ configuration][config]. Refer to sccache documentation for more details.
  [`RUSTFLAGS`]: ../reference/config.md#buildrustflags
  [`build.dep-info-basedir`]: ../reference/config.md#builddep-info-basedir
  +[`build.rustc-wrapper`]: ../reference/config.md#buildrustc-wrapper
  [`build.target-dir`]: ../reference/config.md#buildtarget-dir
  [`cargo doc`]: ../commands/cargo-doc.md
  [`cargo package`]: ../commands/cargo-package.md
  