docs(25.04): update readme on main (canonical#558)

Co-authored-by: Cristovao Cordeiro <cristovao.cordeiro@canonical.com>

Author: clay-lake

README.md

@@ -29,6 +29,8 @@ the moment, the officially supported Chisel releases are:
 \- Noble
 - [ubuntu-24.10](https://github.com/canonical/chisel-releases/tree/ubuntu-24.10)
 \- Oracular
+- [ubuntu-25.04](https://github.com/canonical/chisel-releases/tree/ubuntu-25.04)
+\- Plucky
 
 In each release branch, you'll find a `chisel.yaml` file that defines the Chisel
 release, plus a `slices` folder with all the Slice Definitions Files (SDFs) for