try and keep in line with language used in other manual pages.

try and keep in line with language used in other manual pages.

while i'm here, try and unbundle some of the configuration and
concepts. etherip interfaces can work fine as point to point ethernet
tunnels, they do not need to be configured as part of bridge(4) to
work. ipsec can be configured to protect etherip traffic independently
of whether it's part of a bridge too.