Must be a requirement now that they're a fully reporting company. Not an invitation, just an official notice that a shareholders meeting took place. They may be required to notify shareholders in advance when there are issues that will be voted on, but when nothing comes to a vote it's probably just so shareholders can look into the minutes or video if provided. Obviously there was plenty of advance notice for anyone wishing to attend, a month, though I think the minimum required is something like 12 days notice.