Add to docs that pysparkling has a new dependency pyspark
the dependency will be installed automatically if not found but will need internet .
If user is behind firewall that will manually need to pip install it.-
Say you are trying to instal pysparkling 2.2.x then - `please download pyspark from PiPy https://pypi.org/project/pyspark/ ( just the version 2.2.2) and install it as a regular python dependency using pip.`
This is the error msg thrown if pyspark is not found -