Clarify the idea of continuous improvement as part of the Sprint Backlog
In the section on the Product Backlog, it says that the Product Backlog "lists all features, functions, requirements, enhancements, and fixes that constitute the changes to be made to the product in future releases". It also says that Product Backlog Items (which are presumed to be the only content of the Product Backlog) "have the attributes of a description, order, estimate, and value". The section on the Sprint Backlog says "the set of Product Backlog items selected for the Sprint, plus a plan for delivering the product Increment and realizing the Sprint Goal".
The November 2017 updated modified this paragraph of the Sprint Backlog section of the guide: "The Sprint Backlog makes visible all the work that the Development Team identifies as necessary to meet the Sprint Goal. To ensure continuous improvement, it includes at least one high priority process improvement identified in the previous Retrospective meeting."
This seems to be conflating different things that makes the relationship between Product Backlog Items, the Product Backlog, and the Sprint Backlog more confusing.
A Sprint is defined by a few things: the timebox, the Sprint Goal, and the Sprint Backlog.
Instead of putting the continuous improvement item into the Sprint Backlog, it should be part of the Sprint Goal. I'd also like to see the plan for delivering the Increment and realizing the Sprint Goal as a separate item.
The Sprint Goal and Sprint Backlog can be created in either order. Personally, I've had success with defining a goal and then defining a Sprint Backlog that aligns with that goal. I've also had success defining a Sprint Backlog based on capacity and using the Sprint Goal to align the team with what is most important to achieve at the end of the Sprint. I'd like to see the continuous improvement item added to the Sprint Goal.
I'd then like to see a Sprint Plan that considers the Sprint Backlog (which only consists of some kind of product-centric work) and the Sprint Goal (which encompasses the value to be delivered, to stakeholders via the product as well as the team and/or organization via continuous improvement).
I believe that having a separate Sprint Plan can also focus the discussion of the Daily Scrum event. If the plan aligns with the goal as a separate entity, it becomes easier to discuss variations against plan that are affecting the achievement of the goal.