Store event metadata as issue template
Closes #106 (closed)
This is a suggestion to collect all internal tasks for event orga in hifis/software-services-organization and an actionable announcement template here. Issue template, since we don't (need to) pay for the GitLab version that has custom file templates ;-)
See esp. #106 (comment 25350) and also this MRs companion over in https://gitlab.hzdr.de/hifis/software-services-organization/merge_requests/15