haskell.build should be deployed from last release instead of current master

[Profpatsch]

Describe the bug

Building from release has two implications:

• The start script will refer to the one on current master, meaning if there were breaking changes it will fail with the last release.
• The docs document master instead of the release people are using.

Expected behavior

https://haskell.build should only be updated once per release.

Optionally, we should have a second subdomain https://master.api.haskell.build/, which points to the current master documentation.

[Profpatsch]

I opened another issue in the past that is a subset of this one: #857

[Profpatsch]

We use netlify for deployment, and netlify supports creating subdomains for branches, iff the netlify DNS setup is used: https://www.netlify.com/docs/custom-domains/#branch-subdomains

I suggest we do the following (if possible, or similar):

• Point master to master.api.build.haskell, push with every branch update.
• Create a release branch and point it to release.api.build.haskell.
  • Add “push release branch to release tag” to the MAINTAINERS manual for creating a release
• Change the frontpage at https://haskell.build/ to point to both the master API documentation and the latest release (preferring the latest release).

I don’t have access to the netlify setup, @mboes could you take a look to see if that is possible?

[mboes]

We can't use that because we don't use Netlify for the DNS. We use CloudFlare I believe.

[mboes]

OK we now have two branches, with branch subdomains:

• master.api.haskell.build
• release.api.haskell.build

[mboes]

Buttons to each site added to front page.