Update README.md

[accupham]

update example imports

[aMahanna]

Hi @accupham! Thanks for the contribution

The syntax from arango import ArangoClient is actually intentional due to a shortcut we've placed in the __init__.py file: https://github.com/arangodb/python-arango/blob/main/arango/__init__.py#L2

This allows you to import the ArangoClient without having to write arango.client

[apetenchea]

We appreciate that @accupham, but as Anthony pointed out, the way we document such imports is intentional.
Hence, I'm closing this PR. Feel free to open a new issue in case you stumble upon anything else.