Use https for Documentation button and also pkg-build redirect

[greghendershott]

1. Go to https://pkgs.racket-lang.org/package/sql
2. Click the Documentation button.
3. Its URL is http://pkg-build.racket-lang.org/doc/sql@sql/index.html (http not https)
4. That redirects to http://docs.racket-lang.org/sql/index.html (http not https)

It looks like there are two issues:

1. In step 3, preferably the URL should use https: https://pkg-build.racket-lang.org/doc/sql@sql/index.html

2. To check if whether pkg-build is already set to accept SSL, I manually visited https://pkg-build.racket-lang.org/doc/sql@sql/index.html. The good news is, it works. The bad news is, the subsequent redirect to docs doesn't use SSL even though docs also would accept that.

[jeapostrophe]

I updated pkg-index. I think that pkg-build will redirect correctly only once we change the Cloudflare redirect rules. @mflatt --- I don't have access to our Cloudflare account, so I can't check this. Will you share it with me or take a look?

[mflatt]

It looks set up right in Cloudflare, and https://pkg-build.racket-lang.org seems to work fine.

[SimonLSchlee]

It looks to me like this is fixed? Both urls show https for me.