improve albatros' build script

.albatros

@@ -1,4 +1,5 @@
-#!/usr/bin/env bash
+#!/usr/bin/env nix-shell
+#!nix-shell -p go 
 set -euxo pipefail
 
 go build

README.md

@@ -124,3 +124,4 @@ will be executed.
 
 - [ ] Register the builder programatically
 - [ ] Allow users to define their own set of builders (ones with more CPU+RAM, etc.)
+- [ ] Allow users to choose their image/rootfs