Add comment on difference in dependency map check

Signed-off-by: Sune Keller <absukl@almbrand.dk>

manager/dispatcher/assignments.go

@@ -120,6 +120,9 @@ func (a *assignmentSet) addTaskDependencies(readTx store.ReadTx, t *api.Task) {
 		secretID := secretRef.SecretID
 		mapKey := typeAndID{objType: api.ResourceType_SECRET, id: secretID}
 
+		// This checks for the presence of each task in the dependency map for the
+		// secret. This is currently only done for secrets since the other types of
+		// dependencies do not support driver plugins.
 		if _, exists := a.tasksUsingDependency[mapKey][t.ID]; !exists {
 			assignSecret(a, readTx, mapKey, t)
 		}