message: Mention current default value in `publish.timeout` docs
diff: @@ -813,7 +813,8 @@ The `publish.timeout` key in a config file can be used to control how long
  `cargo publish` waits between posting a package to the registry and it being
  available in the local index.
  -A timeout of `0` prevents any checks from occurring.
  +A timeout of `0` prevents any checks from occurring. The current default is
  +`60` seconds.
  It requires the `-Zpublish-timeout` command-line options to be set.
  