Update README.md

Author: usercode

README.md

@@ -18,9 +18,9 @@ var d1 = await asyncLock.ReaderLockAsync("123");
 d1.Dispose();
 
 //set timeout
-using CancellationTokenSource cancellationToken = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+using CancellationTokenSource cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
 
 //acquire writer lock
-using var d2 = await asyncLock.WriterLockAsync("123", cancellationToken.Token);
+using var d2 = await asyncLock.WriterLockAsync("123", cts.Token);
 
 ```