- "Ns No" is redundant, so reduce it to just "Ns";
- use Li to mark up CPU and system power states because here they are
just strings to be typed literally (add more such mark-up as well);
- the best practice of typesetting tells us to use an en-dash to
indicate a closed range; fortunately, groff_char(7) provides such a symbol.
In addition, consistently use a comma between independent clauses
coordinated by a conjunction.
Pointed out by: ru (mark-up part)
MFC after: 3 days
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