message: Add missing header in `insights` module display output
diff: @@ -348,7 +348,7 @@ impl Display for NetworkInsights {
  }
  f.write_str("connection symmetries:\n")?;
  - writeln!(f, "peer ID ")?;
  + writeln!(f, "peer ID symmetry")?;
  for (peer_id, symmetry) in &self.connection_symmetries {
  write!(f, "{:10} ", peer_id)?;
  symmetry.fmt_time_relative(now, f)?;
  