Move announcement to be compatible with tu delft dark mode

_config.yml

@@ -59,7 +59,6 @@ html:
   comments:
     hypothesis: false
     utterances: false
-  announcement: "Under Development"
 
 
 #######################################################################################
@@ -103,9 +102,12 @@ sphinx:
   recursive_update: false
 
   config:
-    html_theme_options: 
+    html_theme_options:
+
       repository_url: https://gitlab.tudelft.nl/opentextbooks/how-to-manual/
       use_repository_button: True
+      announcement: "Under Development"
+
       logo:
         image_light: content/images/tudelft.png
         image_dark: content/images/tudelft-dark.png