Update README for swift off by default

Change 11277b1f3cfa850c074d3effbb43987b6e6e6391 disabled swift due to
port conflicts but the documentation still states that it is enabled
by default, which can be quite confusing.

While we're there, wrap affected lines to 80 chars.

Change-Id: I9d543f3368bdadadae482c163d814065009ab395