If you keep on reading that paragraph, it says "Currently you cannot specify a node label when submitting a MapReduce job. However, if you submit a MapReduce job to a queue that has a default node label expression, the default node label will be applied to the MapReduce job." So, assign a Yarn label, say "y1" to a few nodes, create a Yarn queue, say "q1" and set its "default node label expression" to "y1", using for example Yarn Queue Manager Ambari view. Then, you can run a MR job on nodes with that label by setting the job's queue, like this:
$ hadoop jar /usr/hdp/current/hadoop-mapreduce-client/hadoop-mapreduce-examples.jar pi -D mapreduce.job.queuename=q1 10 10000
Setting queue name is the way to go, not using labels directly. Setting Yarn queue is supported by all services that can run on Yarn, like Hive, Pig, Oozie, Spark etc.