Swift 5.6 added the `any` keyword as an existential type qualifier. This
PR updates the code examples on the Migrations page to correctly
incorporate this keyword. The following languages are effected: EN, ES,
NL, IT, and ZH.
* Update the main page
* Remove old docs
* Remove old version links and add link to legacy docs
* Fix site URLs in mkdocs.yml
* Move 4.0 docs to top level
* Update fix search index script
* Fix font CSS links
* Update 404 and gitignore
* Update CI and remove all other 4.0 links
* Fix font issue still loading from google
* Update NL index page, remove link to vapor core team (inaccessible)
Co-authored-by: De Bock Benny <bdebock@protonmail.com>
Holly Schilling
Tim Condon
晋先森