firestore: add imports to godoc
Add imports at the top of site page
Fixes
@@ -120,6 +120,7 @@ func f1() {
q := states.Where("pop", ">", 10).OrderBy("pop", firestore.Desc)
//]
//[ Documents
+ // import "google.golang.org/api/iterator"
iter := q.Documents(ctx)
for {
doc, err := iter.Next()
