Extend graph comment.
@@ -766,6 +766,8 @@ TEST_F(HnswMultiIndexTest, duplicate_docid_is_removed)
.set(3, {1, 2})
.set(4, {2, 0, 2, 2});
/*
+ * Graph showing documents at column x row y, origo in lower left corner.
+ *
* 1 3 4
* . . .
* 1 2 4
