CKEditor5 42+ Migration

[tony]

This update may take time to do: https://ckeditor.com/docs/ckeditor5/latest/updating/nim-migration/custom-plugins.html

If you require CKEditor5-Math, try to stay <42 until this is released.

[Witoso]

Just a small nitpick, you can update the editor to version 42+ and use old setups, we are continuing to support them. What you meant I think is that you can't use new installation methods. Thanks!

If you need any help during the migration, let us know :)