Option --channel is not documented

pt-online-schema-change supports option --channel for multi-threaded slaves:

--channel=s Channel name used when connected to a server

using replication channels

But this option is not listed in the user manual at https://www.percona.com/doc/percona-toolkit/3.0/pt-online-schema-change.html

This option certainly exists in version 3.0: https://github.com/percona/percona-toolkit/blob/061e6bb5c1d4454749f81394b9bd88bd4dda192a/lib/MasterSlave.pm