Fixed typo in const in readme

README.md

@@ -5,13 +5,14 @@ This is a one-size-fits-all IPC library to facilitate communication between
 threads and processes. 
 
 For complete examples, see the `examples` directory in the source tree.
+
 ## Signals
 
 Asynchronous signals are automatically enabled if supported. Otherwise, the
 `pcntl_signal_dispatch()` method must be frequently called from your main loop.
-You can test for this using the `ASYNC_SIGNALS` constant:
+You can test for this using the `SIGNALS_ASYNC` constant:
 
-    if (!ASYNC_SIGNALS) {
+    if (!SIGNALS_ASYNC) {
         pcntl_signal_dispatch();
     }