matterbridge/matterbridge.toml.simple

[irc]
    [irc.freenode]
    Server="irc.freenode.net:6667"
    Nick="matterbot"

[mattermost]
    [mattermost.work]
    useAPI=true
    Server="yourmattermostserver.domain"
    Team="yourteam"
    Login="yourlogin"
    Password="yourpass"
    PrefixMessagesWithNick=true

[[gateway]]
name="gateway1"
enable=true
    [[gateway.in]]
    account="irc.freenode"
    channel="#testing"

    [[gateway.out]]
    account="irc.freenode"
    channel="#testing"

    [[gateway.inout]]
    account="mattermost.work"
    channel="off-topic"