don't link to the nightly version of the Edition Guide in stable lints
As reported in rust-lang/rust#143557 for `rust_2024_incompatible_pat`, most future-Edition-incompatibility lints link to the nightly version of the Edition Guide; the lints were written before their respective Editions (and their guides) stabilized. But now that Rusts 2021 and 2024 are stable, these lints are emitted on stable versions of the compiler, where it makes more sense to present users with links that don't say "nightly" in them.
This does not change the link for `rust_2024_incompatible_pat`. That's handled in rust-lang/rust#144006.
