Join a Slack channel.
This adds the user who created the Slack connection that's used by the card to the selected channel.
List of public channels of which the user who created the connection is not a member but can join.
To enter a channel ID manually, select
A maximum of 12,000 public channels will be displayed.
|Channel ID||ID of the channel to join||String||FALSE|
|Channel ID||ID of the channel that was joined||String|