Intelligence of a group and not an individual. For example ants in search for food who leave pheromones for other ants to follow. There is no central control. All communication is kept at a location.
Stigmergy is indirect communication, that is, communication which is not based on transmission to a specific receiver, but rather to a general audience.
I don't understand how this applies to note taking. The sources are quite vague.
Learn how a simple principle from Information Science called "stigmergy" explains how to effectively manage information
I saw it mentioned on the second brain page.