Add a documentation URL alias that always points at the latest release

[zyp]

Amaranth documentation is currently only available under https://amaranth-lang.org/docs/amaranth/<version>/ for releases or https://amaranth-lang.org/docs/amaranth/latest/ for HEAD.
It would be convenient to have an alias like https://amaranth-lang.org/docs/amaranth/stable/ that always points at the latest release.

My use case is that I import the inventory file for cross referencing from my own documentation, and I would like to be able to configure a fixed URL that gives me cross references to the documentation for the latest release.

[whitequark]

My use case is that I import the inventory file for cross referencing from my own documentation, and I would like to be able to configure a fixed URL that gives me cross references to the documentation for the latest release.

Oh, so this is pretty important: that means it can't be a meta redirect, it has to be a copy of the entire documentation tree.

I'm shuddering thinking about the CI mess required to do this. Do you want to write a script, perhaps? The hard part is detecting whether the documentation you just built is for "the stable version", since we don't have an easy to use is_stable() function anywhere.