util/liveiso: Remove coreboot toolchain from todo

The coreboot toolchain is a huge blob and increases the size of the
build a lot. If needed, the specific toolchain can be added before
building the ISO or with `nix-shell` later in the live system, as shown
below.

  $ nix-shell -p coreboot-toolchain.i386

Thus, remove this from the todo list.

Change-Id: Ia24ceb84f202828f1c97d3ba5bafbf6af0361bdb
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62194
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>
diff --git a/util/liveiso/description.md b/util/liveiso/description.md
index b056a9f..48420e6f 100644
--- a/util/liveiso/description.md
+++ b/util/liveiso/description.md
@@ -6,5 +6,4 @@
 
 ## TODO
 - Generate customized bootloader configs; FILO is WIP
-- Add coreboot toolchain
 - Switch to `programs.neovim` when the module is fixed.