Typos that survived in the second revision

I'm showing the section numbers, instead of pages, because they are valid in both revisions.

1. In section 4.6.7 about template rotation, there's some confusion between a template parameter called Dn and D9: the intent is that D9 is the last in the series, so it should be called Dn and D8 is thus Dn-1.
2. In section 4.6.6 there's a spurious comma: template <P1, P2, = default...> should read template <P1, P2 = default...> 
3. In section 4.3.1 [[CONDITION]] is mis-spelled as [[CONDITION]