message: Remove incorrect documents about multirust
diff: @@ -143,11 +143,6 @@ pub fn cargo_home_with_cwd(cwd: &Path) -> io::Result<PathBuf> {
  /// - The `.rustup` directory in the user's home directory, as reported
  /// by the `home_dir` function.
  ///
  -/// As a matter of backwards compatibility, this function _may_ return
  -/// the `.multirust` directory in the user's home directory, only if
  -/// it determines that the user is running an old version of rustup
  -/// where that is necessary.
  -///
  /// # Errors
  ///
  /// This function fails if it fails to retrieve the current directory,
  