Javadoc: Normalize spelling

Author: garydgregory

src/main/java/org/apache/commons/lang3/concurrent/ConcurrentUtils.java

@@ -78,7 +78,7 @@ public T get(final long timeout, final TimeUnit unit) {
 
         /**
          * {@inheritDoc} This implementation always returns <strong>false</strong>; there
-         * is no background process which could be cancelled.
+         * is no background process which could be canceled.
          */
         @Override
         public boolean isCancelled() {