Fix typo in `threads3` hint
@@ -1012,7 +1012,7 @@ hint = """
An alternate way to handle concurrency between threads is to use
a mpsc (multiple producer, single consumer) channel to communicate.
With both a sending end and a receiving end, it's possible to
-send values in one thread and receieve them in another.
+send values in one thread and receive them in another.
Multiple producers are possible by using clone() to create a duplicate
of the original sending end.
See https://doc.rust-lang.org/book/ch16-02-message-passing.html for more info.
