bin/168681: gmirror(8) needs option to limit mirror capacity

[wblock at FreeBSD.org]

Synopsis: gmirror(8) needs option to limit mirror capacity

State-Changed-From-To: open->closed
State-Changed-By: wblock
State-Changed-When: Mon Jan 20 23:32:18 UTC 2014
State-Changed-Why: 
The new Handbook section on gmirror(8) shows how to use gnop(8) to limit
capacity:
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/geom-mirror.html#geom-mirror-existing-drive

http://www.freebsd.org/cgi/query-pr.cgi?pr=168681