I just logged in and checked. To give everyone ability to edit those notes, you are making them all Officer rank which comes with quite a few permissions.
It lets people do a lot more than mess with public notes. It is not something you want 500 people with access to. They can edit the guild info, private notes, add and remove chat in the guild channel, etc.
You can read more here.
You can create a rank in guild that has that permission and have them handle the notes. A selection of folks who are on a fair amount across various times of day.