News categories to tags

From https://gitlab.hzdr.de/hifis/overall/hifis.net/-/issues/327#note_1412618

• Single category only for (hopefully) all posts, additional stuff moved to tags
  • This basically fixes the multi-category problem introduced in https://gitlab.hzdr.de/hifis/overall/hifis.net/-/merge_requests/514/diffs
• redirects from weird multi-category urls that may be in the landscape meanwhile
• Replace static links in new posts with jekyll auto-generated ones

Closes #327 (closed)

_posts/2022/2022-06-17-CfA_Teach-2.md

@@ -18,7 +18,7 @@ excerpt: >
 The second installment of the TEACH event is going to take place **9 November, 2022,** in an online format. 
 It aims at bringing together Training Coordinators, Instructors and Trainers, Personnel Developers and Researchers. 
 The participants will exchange experience and best practices, collaborate and share resources on the whole education life cycle.
-For more impressions have a look at the report from last year's [TEACH conference](https://hifis.net/news/2022/02/14/report-on-teach.html).
+For more impressions have a look at the report from last year's [TEACH conference]({% post_url 2022/2022-02-14-report-on-teach %}).
 
 ## Call for Abstracts is open
 For TEACH 2022, the Call for Abstracts is already open. You can submit a proposal for a talk or discussion, a poster, an elevator pitch or a workshop.