message: TomlProfile::validate_name: disallow a 'doc' dir-name
diff: @@ -536,6 +536,9 @@ impl TomlProfile {
  "package" | "build" | "debug" => {
  failure::bail!("Invalid {}: `{}`", what, name);
  }
  + "doc" if what == "dir-name" => {
  + failure::bail!("Invalid {}: `{}`", what, name);
  + }
  _ => {}
  }
  