Generalizing the course

[eemilhaa]

This issue collects the steps needed to make this course more generally applicable.

### Tasks
- [ ] Add course pages to the [course site repo](github.com/gispocoding/master-training-data). As most of this course is implemented as notebooks, only the contents of `ohjeet/` need to be considered here.
- [ ] Update the [course environment instructions](https://github.com/GispoCoding/python-gis-training/blob/main/ohjeet/kurssiymparisto.md) to be more general.
- [ ] Consider platforms other than Windows for local setup. Linux, macOS.
- [ ] Consider having the option of hosting python + jupyterlab elsewhere, mitigating all need for local installations.