Unclear error while checking FSM spec

[dvilelaf]

Whenever we do not reference a specified event in our rounds, the FSM checker will report something like:

Error: Unreferenced events found in `AutomateAbciApp`
- Events {'NO_MAJORITY', 'DONE'} are defined in the round transitions of `ConditionCheckerRound` but not in `event_to_timeout`
- Events {'NO_MAJORITY', 'DONE'} are defined in the round transitions of `RelayFetcherRound` but not in `event_to_timeout`
- Events {'SETTLE'} are defined in the round transitions of `ExecutorRound` but not in `event_to_timeout`

THis has nothing to do with event_to_timeout and the message should be updated.

[Devanshusisodiya]

@dvilelaf @angrybayblade I've raised a PR for this issue, please review and provide comments.