More Close() docs

graph/iterator/hasa_iterator.go

@@ -247,6 +247,9 @@ func (it *HasA) Stats() graph.IteratorStats {
 }
 
 // Close the subiterator, the result iterator (if any) and the HasA.
+//
+// Note: as this involves closing multiple iterators, only the first error
+// encountered while closing will be reported (if any).
 func (it *HasA) Close() error {
 	var ret error
 

graph/iterator/linksto_iterator.go

@@ -181,6 +181,9 @@ func (it *LinksTo) Result() graph.Value {
 }
 
 // Close our subiterators.
+//
+// Note: as this involves closing multiple subiterators, only the first error
+// encountered while closing will be reported (if any).
 func (it *LinksTo) Close() error {
 	var ret error