That previous link is not ledger specific, you can download a ledger specific app here https://ledger.zendesk.com/hc/en-us/articles/115005174789-How-to-install-and-use-Bitcoin-Cash-BCH-with-Ledger

If you sent the BTC to your nano, it's likely that somebody replayed the transaction onto the BCH network, unless your ledger was using a segeit address.