Boqiang

We need clear documentation on how to run the examples in the example directory. This should include instructions for both Node.js examples and browser examples.

HADOOP-19753 Support HADOOP_LOG_DAEMON_MODE environment variable

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### Description of PR Support a new environment variable HADOOP_LOG_DAEMON_MODE to allow dynamically setting HADOOP_ROOT_LOGGER and HADOOP_LOGFILE to same values as if using --daemon option to run hadoop services hadoop...