Update deployment documentation

[romaricpascal]

What

Update our deployment documentation to reflect that we're hosted on Netlify and no-longer on PaaS

Why

So it's accurate with the current situation

Who needs to work on this

Developers, possibly tech writers

Who needs to review this

Developers, possibly tech writers

Done when

• [x] The deployment documentation reflects that we're now hosted on Netlify

[romaricpascal]

Blocked until we've actually shifted to Netlify.