Fix typo in SpinOnceCore comment (#116980)

Author: mkhlone

src/libraries/System.Private.CoreLib/src/System/Threading/SpinWait.cs

@@ -167,7 +167,7 @@ private void SpinOnceCore(int sleep1Threshold)
             //   - When there are no threads to switch to, Yield and Sleep(0) become no-op and it turns the spin loop into a
             //     busy-spin that may quickly reach the max spin count and cause the thread to enter a wait state, or may
             //     just busy-spin for longer than desired before a Sleep(1). Completing the spin loop too early can cause
-            //     excessive context switcing if a wait follows, and entering the Sleep(1) stage too early can cause
+            //     excessive context switching if a wait follows, and entering the Sleep(1) stage too early can cause
             //     excessive delays.
             //   - If there are multiple threads doing Yield and Sleep(0) (typically from the same spin loop due to
             //     contention), they may switch between one another, delaying work that can make progress.