varnish: point to varnish80 as default package

Also includes release notes.
We will likely move to Vinyl Cache 9 for the 26.05 release due to the
support window in a follow-up change.

doc/release-notes/rl-2605.section.md

@@ -124,6 +124,9 @@
 
 - `lima` has been updated from `1.x` to `2.x`. This major update includes several breaking changes, such as `/tmp/lima` no longer being mounted by default.
 
+- Varnish Cache has been updated to major version 8, `varnish` now refers to `varnish80`. That release contains breaking changes, see [Upgrading to Varnish-Cache 8.0](https://vinyl-cache.org/docs/8.0/whats-new/upgrading-8.0.html).
+  Note that the Varnish 6 LTS release remains available as `varnish60`.
+
 - `eslint` has been updated from version 9 to version 10. Please see https://eslint.org/blog/2026/02/eslint-v10.0.0-released/ for details about the breaking changes included in the update.
 
 - `minio_legacy_fs` has been removed. If you used that package, migrate your data to be compatible with the newest minio and use the package `minio`.

pkgs/top-level/all-packages.nix

@@ -3607,7 +3607,7 @@ with pkgs;
     varnish77Packages
     varnish80Packages
     ;
-  varnishPackages = varnish77Packages;
+  varnishPackages = varnish80Packages;
   varnish = varnishPackages.varnish;
 
   vncdo = with python3Packages; toPythonApplication vncdo;