Issue #25461: Rephrase os.walk() doc

Patch written by Bernt Røskar Brenna.
diff --git a/Misc/ACKS b/Misc/ACKS
index d0ba52f..893fb2d 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1208,6 +1208,7 @@
 Nick Russo
 James Rutherford
 Chris Ryland
+Bernt Røskar Brenna
 Constantina S.
 Patrick Sabin
 Sébastien Sablé