MFC r266417 (bjk):

MFC r266417 (bjk):

Assorted updates to md5.1

Note that the -c argument's parameter is compared against the digest of
the file, not the file. [1]

Update the "current time" parentheticals for notes about reversing
and colliding the hash functions. [1]

Some general mdoc updates.

PR:		docs/188043 [1]
Submitted by:	Jamie Landeg-Jones [1]

git-svn-id: svn://svn.freebsd.org/base/stable/10@281512 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f