General: Update README features and environment variables

This is nice for testing when there isn't xhci controller available or
my usb stack fails :)

script/install-bootloader.sh

@@ -61,7 +61,11 @@ install_grub_uefi() {
 
 	sudo mount $partition2 "$mount_dir"
 	sudo mkdir -p "$mount_dir/boot/grub"
+	if (($BANAN_INITRD)); then
+		sudo cp "$BANAN_BUILD_DIR/grub-uefi-initrd.cfg" "$mount_dir/boot/grub/grub.cfg"
+	else
 		sudo cp "$BANAN_BUILD_DIR/grub-uefi.cfg" "$mount_dir/boot/grub/grub.cfg"
+	fi
 	sudo umount "$mount_dir"
 }