minor ERROR remark

[Alexander Weidauer]

Hi Folks, thanks you for the wonderful bhyve environment. I've start to
install and use it for ubuntu 16.04-lts GENICOM software stuff. One
little remark, please add the closing double qoute in your documentation in
21.7.9. Persistent Configuration ..line

ifconfig_bridge0="addm /|igb0|/ addm /|tap0 <------ HERE
|/
|Thank you and best regards huck. |
||