This displays a news formspec when the player joins. To set the news text make a file named news.txt in your world directory. The contents of this file will display as the news. When changing the contents of the file, there is no need to restart the server for it to update in game.
Players can also type /news to display the formspec at any time.
Players with the news_bypass privilege will not see the formspec when they sign in, but can still use the /news command.