Split the docs website to its own repo

[thehowl]

#1564 adds the Netlify configuration file at the root directory. This should be literally anywhere else (like docs, misc/docusaurus, /dev/null). However, Netlify doesn't make it easy for us.

While discussing it with the team, we agreed to:

• Create a new repository to hold the designs and configuration data (docusaurus, netlify) for the docs website
• Create a CI action that, when committing to master in gno, pushes any changes to the docs/ directory to the new repository
• Remove the misc/docusaurus directory here (only keep the documentation files themselves on this repo)