Make Swift.org/migration the landing page instead of a redirect

[hborla]

Currently, Swift.org/migration redirects to https://www.swift.org/migration/documentation/migrationguide/. We should fix this to make Swift.org/migration the landing page.

[mattmassicotte]

I think this is being done here: swiftlang/swift-org-website#726

[hborla]

No, that PR is just updating the link on the website for when this issue is fixed. cc @shahmishal

[mattmassicotte]

ah, well at least related 😅

[shahmishal]

What should the landing page contain? I am assuming other migration guides and link to Swift 6 migration doc.

[hborla]

What should the landing page contain? I am assuming other migration guides and link to Swift 6 migration doc.

I think the landing page should be this page: https://www.swift.org/migration/documentation/migrationguide/

I don't think the other older migration guides are super relevant anymore. We can evolve the landing page if/when there's a future language mode to document the migration for.