You will be able to add a note for your connection by finding that specific connection and then clicking on the ellipsis (⋯) - More Menu - on the right-hand side of the connection row and selecting Note option.

Once you click on the Note option, a popup will appear presenting the Note box where you will be able to enter the note you wish. The max number of characters is 200.

You will always be presented with the info on the last time the note was updated for the specific connection.

It will also be possible to delete a Note by clicking on the Delete button.

In case there is a Note added for the connection, the Note icon will turn purple so it will be clear in the list of Connections which one actually have a note.