message: Update path to `config.toml.example`
  In rust-lang/rust moved
  `config.toml.example` from `src/bootstrap/` to the project root.
  Instructions in rust-lang/rust were updated, but this instance was not.
diff: @@ -263,7 +263,7 @@ have it available so you can understand the types. Here's how you can compile it
  yourself. From the top level directory where `x.py` is located run:
  ```bash
  -cp src/bootstrap/config.toml.example config.toml
  +cp config.toml.example config.toml
  ```
  Next open up `config.toml` and make sure these two lines are set to true:
  