Show number of YoY histogram points when detailed=True

[kandersolar]

• Code changes are covered by tests
• Code changes have been evaluated for compatibility/integration with TrendAnalysis
• [ ] New functions added to __init__.py
• [ ] API.rst is up to date, along with other sphinx docs pages
• [ ] Example notebooks are rerun and differences in results scrutinized
• Updated changelog

See #298. I think detailed=True is not used in the example notebooks anywhere; worth using that somewhere to (1) highlight that it exists, and (2) see it in action for ourselves?

RTD failure is addressed by #325

[mdeceglie]

LGTM!