remove dead links

config.yml

@@ -29,9 +29,6 @@ languages:
           > - Weitere [Kontaktmöglichkeiten](/posts/contact)
     menu:
       main:
-        - name: Über
-          url: /posts/helloworld
-          weight: 1
         - name: Kontakt
           url: /posts/contact
           weight: 1000
@@ -48,7 +45,6 @@ languages:
           > - When? 26.9 - 28.9.2025
           > - Where? [Heizhaus Nürnberg](https://heizhaus.org/) ([Wandererstr. 89c, 90431 Nürnberg](https://osm.org/go/0D6zlBi~x-?way=37685652))
           > - Element/Matrix Channel: https://matrix.to/#/#quellcode:chat.heizhaus.org
-          > - DECT: We will have DECT, so bring your phone! All further details are available [here](/en/posts/dect).
           > - Other [Contacts](/posts/contact)
     menu:
       main: