Remove outdated datarecorder script from repository

Summary

The eta-datarecorder (https://git.ptw.maschinenbau.tu-darmstadt.de/eta-fabrik/public/eta-datarecorder) has been updated. This needs to be reflected in this repository.

Task

Remove the data_recorder.py script from the repository, and update the documentation file examples.rst to refer to the repository instead.

What is your goal?

The file has been removed and the Connectors section of the Usage examples documentation chapter is updated to refer to the eta-datarecorder repository linked above. The docs have been compiled and proofread locally.