Update broken link to Cardano documentation portal

Author: nbacquey

nix/docker/README.md

@@ -230,8 +230,7 @@ Note that once ledger state is converted, the cardano-node container will need
 to be run with a node configuration aligned with the new ledger state type,
 otherwise ledger replay from genesis will re-occur.
 
-For more info, see the [UTxO Migration Guide](https://ouroboros-consensus.cardano.intersectmbo.org/docs/for-developers/utxo-hd/migrating/).
-
+For more info, see the [UTxO Migration Guide](https://ouroboros-consensus.cardano.intersectmbo.org/docs/references/miscellaneous/utxo-hd/migrating/).
 
 ## Legacy Tracing System
 Cardano-node now defaults to using the new tracing system.  The legacy tracing