Merge pull request #4116 from rust-lang/chriskrycho/mention-rustc-book

Link to tests section of rustc book for `cargo test -- --help` docs

src/ch11-02-running-tests.md

@@ -13,7 +13,12 @@ binary. To separate these two types of arguments, you list the arguments that
 go to `cargo test` followed by the separator `--` and then the ones that go to
 the test binary. Running `cargo test --help` displays the options you can use
 with `cargo test`, and running `cargo test -- --help` displays the options you
-can use after the separator.
+can use after the separator. Those options are also documented in [the “Tests”
+section][tests] of the [the rustc book][rustc].
+
+[tests]: https://doc.rust-lang.org/rustc/tests/index.html
+[rustc]: https://doc.rust-lang.org/rustc/index.html
+
 
 ### Running Tests in Parallel or Consecutively