Zap obsolete bridge section

Zap obsolete bridge section

netstart(8) lost bridge specific functionality in 2009.

Replace "bridge" with "X" in the existent sentence and you'll get an
obvious unhelpful statement:

	If the network interface is a bridge, the options described in
	the bridge section of the ifconfig(8) manual page apply.

Since the following example is no longer special in any way, remove it.

OK deraadt