Possible error in python import statement in README

[chbroecker]

After following the README instructions to setup the generate_parameter_library in python today, I continued to receive an ImportError. I looked into the generated parameter code and realized that my import was wrong and I believe there is an error in the README.

The top level key in the turtlesim_parameters.yaml is turtlesim while the import statement in the turtlesim/turtlesim.py file reads

from turtlesim_pkg.turtlesim_parameters import turtlesim_parameters

The last part of the import should be the top level key of the yaml file right? So only:

from turtlesim_pkg.turtlesim_parameters import turtlesim

I can create a PR that fixes this small error but I first wanted to make sure that I haven't missed anything obvious.

Also for completeness sake, the _pkg should also be removed if the file is called turtlesim/turtlesim.py right?