Update RxRingBuffer.java

Yet another undelrying

Author: akarnokd

src/main/java/rx/internal/util/RxRingBuffer.java

@@ -413,7 +413,7 @@ public Object peek() {
         synchronized (this) {
             Queue<Object> q = queue;
             if (q == null) {
-                // we are unsubscribed and have released the undelrying queue
+                // we are unsubscribed and have released the underlying queue
                 return null;
             }
             o = q.peek();