Clarify that content-id referencing for newly created entities also works for entities created by an action

Section 11.7.4 Referencing Returned Entities explicitly mentions "insert requests".

Section 11.5.5.1 Invoking an Action states that

Actions that create and return a single entity follow the rules for entity creation and return a Location header that contains the edit URL or read URL of the created entity.

Clarify that referencing returned entities also works for entities created via an action.

Also clarify whether that requires a bound action to specify an EntitySetPath and an action import to specify an EntitySet, or whether it is sufficient that the server knows how to identify the returned entity.