Update readme.md

Author: dclong

readme.md

@@ -10,6 +10,19 @@ as it leverages the Docker image
 [dclong/python-portable](https://github.com/dclong/docker-python-portable) 
 to build portable Python environments.
 
+## Tips on Portable Python Environment for PySpark 
+
+The Python library `pyspark` is not needed as Spark has a pyspark library come with it 
+and it is used when you submit PySpark applications to the cluster. 
+Some Python libraries might have the Python library `pyspark` as one of its dependencies. 
+If you have such a library installed 
+and thus have the Python library `pyspark` installed into the portable Python environment, 
+you can simply remove the `pyspark` library.
+    
+    :::bash
+    rm -rf /opt/python/lib/site-packages/pyspark*
+
+
 ## Pre-developed Scripts for Building and Packing Portable Python
 
 | Script               | Build Command                 | Output Env               | Comments                                                           |