Remove mention of defunct mailing list from acl / mac man pages.

Sponsored by: Klara, Inc.
Reviewed by: kevans
Differential Revision: https://reviews.freebsd.org/D41923

(cherry picked from commit b653faaa19c47a4a7e488e5ead738b7ae44ffe8b)

Fix typos in acl_get_entry(3) manual page.

Sponsored by: Klara, Inc.
Reviewed by: kevans
Differential Revision: https://reviews.freebsd.org/D41924

(cherry picked from commit c34fce8a039935e06ed84db1395d7d2c551e5a7c)