ADD new folder structure noppe/guide_for_teachers/...

[katrite]

Modularize Noppe teachers guide to shorter units

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[rkronberg]

Please note that changing folder structure will also change old URLs, so redirects may be good to add :)
https://github.com/CSCfi/csc-user-guide/blob/master/STYLEGUIDE.md#redirecting-pages

I would also recommend using shorter filenames to condense the URLs, but this is just a personal opinion.