gitcodev: Lesson 3 contains material from the Software Carpentry Workshop

[wmotion]

File ./Lesson3.md contains a reference to the dataset of the Python lesson of the SWC
https://github.com/4TUResearchData-Carpentries/workshop_notes/blame/c0274740457f7b9c6fb6b8062040b11d94f75150/Lesson3.md#L116

The references should rather be aligned with either the materials of Lessons 1 and 2 or to the exercises of gitcodev.