fix location of acknowledgements.txt in doc

Author: rouilj

RELEASE.txt

@@ -14,7 +14,7 @@ Roundup release checklist:
       website/www/index.txt
       website/www/conf.py  (also update copyright)
 2a. Update license end date in COPYING.txt
-2b. Update website/www/docs/acknowledgements.txt (add section for
+2b. Update doc/acknowledgements.txt (add section for
     release, churn contributers etc.).
 3.  Update documentation
       doc/announcement.txt