Please look on this official osm page:
https://wiki.openstreetmap.org/wiki/Key:note

Description
A note to yourself or to other mappers. Show/edit corresponding data item.

A note is used to inform other mappers about non-obvious information about an element, the author's intent when creating it, or hints for further improvement. It is usually recorded against a node, way or relation.

I think these notes are quite valid in this context.