message: record the docsrs commit in rustwide builds
diff: @@ -380,7 +380,7 @@ impl RustwideBuilder {
  Ok(BuildResult {
  build_log: storage.to_string(),
  rustc_version: self.rustc_version.clone(),
  - docsrs_version: String::new(), // FIXME(pietro): fix
  + docsrs_version: format!("docsrs {}", ::BUILD_VERSION),
  successful,
  cargo_metadata,
  target: target.to_string(),
  