Bundle field validation with Feature in Drupal 8
It looks like the field validation module has it's own configuration entity type.  This means that in the feature editor there should be a section labeled something like Field Validation Rule Sets.

Select the appropriate configuration under this section to include it with your content type feature.

I assume that you know that to include the content definition you need a minimum of the content type, the individual fields (storage and field settings), the entity form display, and entity view display.  

There may be other specialty items like language settings here.  Enter the machine name of the content type in the feature editor search field (after checking include conflicts) to find them.  NOTE: Red indicates they are part of another feature and you may not need to include them.