Update training-slides/src/deconstructing-send-arc-mutex.md

Co-authored-by: Jonathan Pallant <[email protected]>

training-slides/src/deconstructing-send-arc-mutex.md

@@ -1,7 +1,7 @@
 <!-- markdownlint-disable MD031 MD033 MD037 -->
 # Deconstructing Send, Arc, and Mutex
 
-## `tread::spawn` Function
+## `thread::spawn` Function
 
 ```rust ignore
 pub fn spawn<F, T>(f: F) -> JoinHandle<T>