message: adjust README for rustc-dev
diff: @@ -31,8 +31,10 @@ Miri heavily relies on internal rustc interfaces to execute MIR. Still, some
  things (like adding support for a new intrinsic or a shim for an external
  function being called) can be done by working just on the Miri side.
  -To prepare, make sure you are using a nightly Rust compiler. Then you should be
  -able to just `cargo build` Miri.
  +To prepare, make sure you are using a nightly Rust compiler. You also need to
  +have the `rust-src` and `rustc-dev` components installed, which you can add via
  +`rustup component add rust-src rustc-dev`. Then you should be able to just
  +`cargo build` Miri.
  In case this fails, your nightly might be incompatible with Miri master. The
  `rust-version` file contains the commit hash of rustc that Miri is currently
  @@ -41,7 +43,7 @@ to wait for the next nightly to get released. You can also use
  [`rustup-toolchain-install-master`](https://github.com/kennytm/rustup-toolchain-install-master)
  to install that exact version of rustc as a toolchain:
  ```
  -rustup-toolchain-install-master $(cat rust-version) -c rust-src
  +rustup-toolchain-install-master $(cat rust-version) -c rust-src -c rustc-dev
  ```
  Another common problem is outdated dependencies: Miri does not come with a
  