Mistake in the documentation “Working with Joins”

[janaperedni]

Example 1:
orders to customers : many orders per the same customers (makes sense)

Example 2:
2.1 post to post_topics : many posts to one post_topic
why not one to many? see screenshot 3, there it has one to many

2.2 post_topics to topics : one post_topics to many topics
the same question