message: Fix README typo
  "behaivours" -> "behaviours".
  Just something I noticed while reading
diff: @@ -65,7 +65,7 @@ in your program, and cannot run all programs:
  not support networking. System API support varies between targets; if you run
  on Windows it is a good idea to use `--target x86_64-unknown-linux-gnu` to get
  better support.
  -* Weak memory emulation may [produce weak behaivours](https://github.com/rust-lang/miri/issues/2301)
  +* Weak memory emulation may [produce weak behaviours](https://github.com/rust-lang/miri/issues/2301)
  unobservable by compiled programs running on real hardware when `SeqCst` fences are used, and it
  cannot produce all behaviors possibly observable on real hardware.
  