util/liveiso: Make neovim the default editor

Make neovim the default editor and create an alias for vim.

The NixOS module for neovim is currently broken. Thus, add a note to
`description.md` to switch to that later.

Change-Id: I9345a6e32f3035565e55e50579c97121b4987d83
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57393
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/liveiso/common.nix

@@ -16,10 +16,17 @@
 		isoName = "${config.isoImage.isoBaseName}-${config.system.nixos.label}-${pkgs.stdenv.hostPlatform.system}.iso";
 	};
 
+	environment = {
+		variables = {
+			EDITOR = "nvim";
+			VISUAL = "nvim";
 			# Tell the Nix evaluator to garbage collect more aggressively.
 			# This is desirable in memory-constrained environments that don't
 			# (yet) have swap set up.
-	environment.variables.GC_INITIAL_HEAP_SIZE = "1M";
+			GC_INITIAL_HEAP_SIZE = "1M";
+		};
+		shellAliases.vim = "nvim";
+	};
 
 	boot = {
 		kernelParams = [

util/liveiso/description.md

@@ -9,3 +9,4 @@ NixOS configuration files for testing purposes and for working on firmware.
   Will be usable from the next NixOS release.
 - Generate customized bootloader configs; FILO is WIP
 - Add coreboot toolchain
+- Switch to `programs.neovim` when the module is fixed.