message: document SourceId::from_cwd
diff: @@ -167,6 +167,9 @@ impl SourceId {
  SourceId::new(Kind::Directory, url)
  }
  + /// Create a SourceId from the current working directory filesystem path.
  + ///
  + /// Pass absolute path
  pub fn from_cwd(path: &Path) -> CargoResult<SourceId> {
  let url = path.to_url()?;
  Ok(SourceId {
  