runtime: fix a typo in comment of MAX_LIFO_POLLS_PER_TICK (#7520)

Author: mxsm

tokio/src/runtime/scheduler/multi_thread/worker.rs

@@ -230,7 +230,7 @@ type Notified = task::Notified<Arc<Handle>>;
 
 /// Value picked out of thin-air. Running the LIFO slot a handful of times
 /// seems sufficient to benefit from locality. More than 3 times probably is
-/// overweighing. The value can be tuned in the future with data that shows
+/// over-weighting. The value can be tuned in the future with data that shows
 /// improvements.
 const MAX_LIFO_POLLS_PER_TICK: usize = 3;