Add errorDef properties table to spec doc

[tsurdilo]

The spec doc is missing definition of error def. Here is the associated schema def- https://github.com/serverlessworkflow/specification/blob/main/schema/errors.json#L29

This should be added to https://github.com/serverlessworkflow/specification/blob/main/specification.md#workflow-error-handling

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.