Add llvm to list of apt packages in the readme

This is needed for `llvm-objcopy`.

BUG=b:250621098
TEST=None

Change-Id: Ic1631acce984120e878a8edda77101b7cce83802
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crdyboot/+/3936171
Commit-Queue: Esther Shimanovich <eshimanovich@google.com>
Tested-by: Nicholas Bishop <nicholasbishop@google.com>
Reviewed-by: Esther Shimanovich <eshimanovich@google.com>
Auto-Submit: Nicholas Bishop <nicholasbishop@google.com>
diff --git a/README.md b/README.md
index 8e0c609..fb2e395 100644
--- a/README.md
+++ b/README.md
@@ -61,7 +61,7 @@
 
 Install tools used for image signing and running in a VM:
 
-    sudo apt install efitools gdisk ovmf ovmf-ia32 qemu-system-x86 sbsigntool
+    sudo apt install efitools gdisk llvm ovmf ovmf-ia32 qemu-system-x86 sbsigntool
 
 After installing qemu, add your user to the `kvm` group. You will need
 to log out and back in for this to take effect: