doc improvement.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@3785 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/model/Queue.java

@@ -529,6 +529,10 @@ public class Queue extends ResourceController {
         /**
          * Returns true if the execution should be blocked
          * for temporary reasons.
+         *
+         * <p>
+         * This can be used to define mutual exclusion that goes beyond
+         * {@link #getResourceList()}.
          */
         boolean isBuildBlocked();