make the docs public

[ccbrown]

This makes the docs public (mostly)!

• Changes the titles of the Football and Soccer pages to "Gridiron Football" and "Association Football (Soccer)".
• Changes the example preview image from an NFL image to an EPL image.
• Upgrades GraphiQL to get a bug fix for search links not working.
• Fixes the login page not actually sending you to your destination afterward.
• Adds a version component to GraphiQL URLs. This isn't actually used yet, but it's good to have there for permalinks if we ever support GraphQL exploration in additional major API versions.
• Moves the authentication wall so that the only pages that require authentication are the reference and explorer pages. As a side-effect, all other pages are now 100% statically rendered and load crazy fast.

[ghost]

LGTM