For "parent" node, how do I show list of child nodes related by child field of type "Entity Reference"?
Thanks in part to @Niall Murphy's response, I was able to find a Drupal Community Doc that got me further along, though I had to do some translation from Drupal-7 terminology to Drupal-8 terminology before I reached a solution/answer. I've updated the Doc accordingly so you can read it for the solution/answer details. 

Note: No additional modules were needed. I was able to do everything with freshly-installed out-of-the-box Drupal 8.0.2 functionality.