docs: fix redirects

[ExposedCat]

Replaces incomplete #124, closes #123

This PR solves the "404 issue" by

• Migrating outdated links within documentation, types and packages README files
• Moving redirects from client-side plugin to vercel config
• Enabling URL cleaning, i.e. serving /path/file from /path/file.html

While it seemed intentional to keep redirects client-side due to the SSG nature of the app, if any URL present in redirects config would be opened right away, e.g. from package README, Vercel would render 404 before client-side redirect plugin would trigger.