Updated Hadoop Compatible File System (markdown)

Hadoop-Compatible-File-System.md

@@ -111,6 +111,8 @@ $ cp ./seaweedfs-hadoop3-client-x.x.x.jar share/hadoop/common/lib/
 Now you can do this:
 ```
 $ cd ${HADOOP_HOME}
+// optionally adjust hadoop memory allocation
+$ export HADOOP_CLIENT_OPTS="-Xmx4g"
 $ bin/hdfs dfs -ls /
 
 # if you did not set fs.defaultFS in etc/hadoop/core-site.xml