Update copyright to CC0

[oskarth]

Addresses https://github.com/vacp2p/vac.dev/issues/73 by ensuring write-ups are CC0.

This is already basically the case but this just makes it explicit, similar to what we've done for RFC specs.

Checkbox for authors to fill in:

• [x] @oskarth
• [x] @decanus
• [x] @jm-clius
• [x] @staheri14
• [x] @kaiserd
• [x] @s1fr0
• [x] @rymnc
• [x] @thecirce

https://github.com/vacp2p/vac.dev/tree/staging/_data/authors

https://creativecommons.org/share-your-work/public-domain/cc0/

---

Please confirm by writing a comment/reviewing this PR with:

"I acknowledge that research posts are placed under CC0."

[oskarth]

I acknowledge that research posts are placed under CC0.

[decanus]

I acknowledge that research posts are placed under CC0.

[fryorcraken]

I acknowledge that research posts are placed under CC0.

[staheri14]

I acknowledge that research posts are placed under CC0.

[oskarth]

Thanks everyone!