Improving the logic of the simplification example

[matatk]

If the simplification example is processed to only show critical info, the sentence will be "Therefore school will close at 1 pm on Tuesday"—but in this case the "Therefore" isn't really needed and could be confusing.

https://github.com/w3c/personalization-semantics/blob/26ca604dff2bedbba88715214035014e34947fb9/content/simplification.html#L21

I think we should have the "Therefore" outside of the "critical" part, so it makes more sense when filtered.

Note: I filed PR #186 to fix the typos, but I am filing this as a separate issue because it may need a little discussion.