Share folders in Notes on iCloud.com
You can invite people to view and edit a folder in Notes on iCloud.com. When you share a folder, the people you invite can view and edit the folder, as well as any subfolders and notes within it, even if someone else has a link to the folder.
When you share a folder, the shared icon 
appears next to the folder in the sidebar.
While you can view shared folders on iCloud.com on a phone, you must go to iCloud.com on a tablet or a computer to share folders and manage sharing.
However, you can still make updates to shared folders and delete shared folders on iCloud.com on an iPhone.