net/td-system-info: New port

Printing basic system information and system maintenance

- Submitter becomes Maintainer

PR:		https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=255576
Reported by:	Thomas Dreibholz <dreibh@iem.uni-due.de>
Approved by:	garga (mentor)
Differential Revision:	https://reviews.freebsd.org/D30098