`build-type` docs have dead link to `BuildType` haddocks

**What is wrong with the docs?**

As of today, [these docs](https://cabal.readthedocs.io/en/stable/cabal-package.html#pkg-field-build-type) refer to haddocks for Cabal-the-library to find out the valid values for `build-type`,

> Build types are the constructors of the [BuildType](https://hackage.haskell.org/package/Cabal/docs/Distribution-PackageDescription.html#t:BuildType) type.

but that link leads to a 404. Specifically, it redirects to the current version of Cabal, where I suppose there's no longer a module at that path: https://hackage.haskell.org/package/Cabal-3.10.2.1/docs/Distribution-PackageDescription.html#t:BuildType

**Additional context**

None really.

Rather than just fixing the link, I think it'd be better to if the allowed values were just documented directly, because I am reading the docs for cabal-install, not Cabal-the-library, and I shouldn't have to care about how the latter's API looks.