In that part of the man page, one can read "This parameters" instead of "This parameter". This happens a few times in the man page.
Fixed for 3.0.23. Thanks.
This is not fixed.
$ grep -i 'this parameters' samba-3.0.23a/docs/manpages/smb.conf.5 | wc -l
It is fixed. The fix has just not been released yet.