Issue #13530: Document os.lseek() result

Patch written by Jérémy Anger.
diff --git a/Misc/ACKS b/Misc/ACKS
index 0f92165..24923da 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -30,6 +30,7 @@
 Erik Andersén
 Oliver Andrich
 Ross Andrus
+Jérémy Anger
 Jon Anglin
 Éric Araujo
 Alicia Arlen