About BS.1770-5

[zsliu98]

Thanks for the great library! The link of ITU-R BS.1770-4 in README is broken (potentially because of the release of the new standard). I have just done a quick comparison between BS.1770-4 and BS.1770-5. It seems that the only difference is an additional attachment (which seems unrelated to this library). Could you confirm this and update the link?