Inserts an event into the WorkflowActionHistory table, in the workflow's companion data. The three parameters to this function are required. The rest of the row's values are computed or inherited from local data.
Takes three parameters:
The first parameter is the workflow action.
The second parameter is the message associated with the action.
The third parameter is a comma-delimited list of users for the current workflow step,. See wfComputeStepUserList for a function which computes the current list.