Fix old links to software.hifis.net

CONTRIBUTING.md

_posts/2019/12/2019-12-20-Welcome-Post.md

_posts/2020/01/2020-01-07-contributing-in-4-simple-steps.md

...ts/2020/04/2020-04-15-hifis-software-workshops-in-2020.md

...ts/2020/06/2020-06-01-hifis-software-helpdesk-launched.md

_posts/2020/10/2020-10-30-hifis-meeting-wrapup.md

_posts/2021/01/2021-01-21-survey-results-community.md

_posts/2021/02/2021-02-09-helmholtz-gitlab.md

_posts/2021/03/2021-03-26-survey-results.md

_roadmap/software/2019-12-01-tasks.md

_roadmap/software/2020-03-01-tasks.md

_roadmap/software/2020-06-01-tasks.md

_roadmap/software/2020-09-01-tasks.md

_roadmap/software/2021-02-26-tasks.md

_roadmap/software/2021-06-30-tasks.md

faq.md

publications.md

services/overall/survey.html