Package check result: NOTE

Check: CRAN incoming feasibility, Result: NOTE
  Maintainer: ‘Maximilian Mücke <muecke.maximilian@gmail.com>’
  
  Found the following (possibly) invalid URLs:
    URL: https://www.ecb.europa.eu/ecb/contacts/working-hours/html/index.en.html
      From: man/ecb_euro_rates.Rd
      Status: 503
      Message: Service Unavailable
    URL: https://www.ecb.europa.eu/stats/policy_and_exchange_rates/euro_reference_exchange_rates/html/index.en.html
      From: man/ecb_euro_rates.Rd
      Status: 503
      Message: Service Unavailable