added software events

_events/2019-12-11-snakemake-introduction-workshop.md

_events/2020-01-20-the-carpentries-instructor-training.md

_events/2020-03-09-helmholtz-gpu-hackathon.md

_events/2020-03-31-the-carpentries-workshop.md

_events/2020-04-20-software-carpentries-workshop.md

_events/2020-04-21-the-carpentries-workshop.md

_events/2020-05-12-ready-script-for-publication.md

_events/2020-06-09-GitLab-Software-Development-Teams.md

_events/2020-06-22-software-carpentries-workshop.md

_events/2020-08-19-the-carpentries-workshop.md

...s/2020-09-02-series-of-online-research-software-events.md

_events/2020-09-18-git-and-gitlab.md

_events/2020-10-07-the-carpentries-workshop.md

_events/2020-11-04-erste-schritte-in-python.md

_events/2020-11-12-bring-script-make-ready-publication.md

...-GitLab-Software-Development-Teams-2020-12-15-sd4teams.md