README.md better explanation of Parsing Zone Files

[taich001]

Add imports
change print() cause of python3

>>> import blockstack_zones
>>> import json
>>> zone_file_object = parse_zone_file(zone_file)
>>> print(json.dumps(zone_file_object, indent=4, sort_keys=True))

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[philipcristiano]

This would be awesome to get merged, I ran into the import issue on py3!

@jcnelson mind taking a look?

[jcnelson]

Hey @philipcristiano, @taich001,

Thank you for sending this PR! Unfortunately, we have no plans to move to Python 3, and are in the process of removing all of the Python modules in this organization (we're moving to Typescript and Rust). However, please feel free to maintain a Python 3 fork if you find it useful 👍