docs: mark registration as closed (#103)

Signed-off-by: Sven Trieflinger <[email protected]>

docs/community/events/csc23/index.md

@@ -15,20 +15,8 @@ place on November 30th. Everyone interested is welcome to attend! However,
 seats for in-person participation are limited and registration is required
 for both in-person and virtual attendance in order to facilitate our planning.
 
-!!! important
-    Please use the eventcode **CSC23** to register on the EventXP platform.
-    On the desktop version of the EventXP website, you must enter it in the
-    the upper right corner of the UI. For the iOS mobile version, you
-    will find a button at the very top. For Android use the hamburger menu
-    button (:material-menu:).
-
-<a href="https://register.event-xp.com" class="md-button md-button--primary">
-    Register
-</a>
-
-!!! warning
-    Registration will close on November 24th for both in-person and virtual
-    attendance.
+!!! warning "Registration closed"
+    Registration is closed since November 24, 2023 (CET).
 
 ## Program
 

overrides/main.html

@@ -1,5 +1,5 @@
 <!---
-  ~ Copyright (c) 2021 - for information on the respective copyright owner
+  ~ Copyright (c) 2021-2023 - for information on the respective copyright owner
   ~ see the NOTICE file and/or the repository https://github.com/carbynestack/carbynestack.github.io.
   ~
   ~ SPDX-License-Identifier: Apache-2.0
@@ -12,7 +12,7 @@
 
 {% block announce %}
 <div class="announcement-bar">
-  CarbyneStackCon '23 is around the corner. For registration and more
-  information see <a href="/community/events/csc23/">here</a>. 
+  CarbyneStackCon '23 is around the corner. For more information see
+  <a href="/community/events/csc23/">here</a>. 
 </div>
 {% endblock %}