In Hyperledger Fabric, the correct subcommand to add a peer to a channel is peer channel join. This
command is used by a peer node to join an existing channel. The command requires a block to be
specified which typically is the genesis block of the channel, allowing the peer to synchronize with
the channel's ledger from the beginning. Other commands like peer channel fetch, peer channel
create, and peer channel update serve different purposes. peer channel fetch retrieves blocks from a
channel, peer channel create is used to set up a new channel, and peer channel update modifies
channel settings. Thus, peer channel join is the specific command used to connect a peer to a
channel.
