This also renames the category of the diagrams post in order to be in
line with the other tutorials.

Update 2021-06-10-story-hts.md, repositioned paragraph about tests from HelmholtzAI section to 'what has been done'

Update 2021-06-10-story-hts.md, added detailed numbers and enhanced the information in the HTS blog post.

* Adds missing team members from software.hifis.net to the team data of
hifis.net
* Names non-HIFIS authors and contributors explicitly in the posts and
events

Introduce a structure in the events directory to structure the list of
events better.