Incorrect examples in synthetic spreads section

[bduga]

Section

https://www.w3.org/TR/epub-33/#spread

Describe the problem

Examples 58, 59, and 60 all show 3 pages of content turning into 4 pages when spreads are enabled. It appears the intent is to duplicate the right hand page of a spread as the left hand page of the next spread.

Describe the fix or new feature you propose

Rework the sample to show spreads as [1,2], [3,-] instead of [1,2], [2,3].

[sueneu]

This is a good catch!

Perhaps after we finalize the deprecations etc #2841 we should rework this.

It might be helpful to find an example that looks like a book to make the example even clearer.

Do we want to consider reading direction here? Offer a Hebrew or Japanese example too?