workshop 8: section order

[amael-ls]

It could be relevant to reorder the sections of this workshop by inserting section 8 between 4 and 5:
1, 2, 3, 4, 8, 5, 6, 7 (tried on students today).
Indeed, section 5 is about changing the basis, but basis has not yet been explained and will not be before section 8. If the section is not moved entirely (pdf are kind of tricky to explain), maybe moving slides 94-96 to the introduction would work too.