Update README.md

Author: neakor

README.md

@@ -12,4 +12,4 @@ Provides locking-free synchronization of a mutable `Int`. It provides higher per
 Provides locking-free synchronization of a mutable object reference. It provides higher performance than using locks to ensure thread-safety and synchronization correctness.
 
 ### `CountDownLatch`
-A utility class that allows coordination between threads. A count down latch starts with an initial count. Threads can then decrement the count until it reaches zero, at which point, the suspended waiting thread shall proceed.
+A utility class that allows coordination between threads. A count down latch starts with an initial count. Threads can then decrement the count until it reaches zero, at which point, the suspended waiting thread shall proceed. A `CountDownLatch` behaves differently from a `DispatchSemaphore` once the latch is open. Unlike a semaphore where subsequent waits would still block the caller thread, once a `CountDownLatch` is open, all subsequent waits can directly passthrough.