Adds a user to a thread.
$threadAddMember[Thread ID;User ID]
(Type: Snowflake || Flag: Required): The ID of the thread channel to add the user to.
(Type: Snowflake || Flag: Required): The user to add to the thread.
$nomention $var[thread;$startThread[Cool Thread;$channelID;;60;yes]] $threadAddMember[$var[thread];$authorID]