How to add a notice in the next meeting section

To add a notice over the Next meetings section of the website in case there is a modification for a meeting, click Appearance / Widgets on the left pane and edit the Next meetings widget in the Primary box (see the screenshot below). Click Save, then click Empty Cache on the top, and reload the webpage to check that the modifications have been taken in account. After the event has passed, delete the notice from the website.