While there, remove .Tn from man pages.
Also remove an obsolete comment about the 80386.
MFC after: 1 week
Sponsored by: Klara, Inc.
Reviewed by: kevans, allanjude
Differential Revision: https://reviews.freebsd.org/D38373
While the correctness of the supported hash algorithms can be tested
with the built-in self-test feature, these test cases are meant to
detect changes in the output format.
A follow-up commit will improve the compatibility with the coreutils
versions of the hash programs, and these tests should detect any
unintended side-effects of such a change on existing functionality.
