message: sdcard-image-utils: add readme for the utils folder
diff: # Scripts
  +
  +Dragonboard helper scripts to build a `.img` file
  +
  +#### Prerequisites
  +The script has been tested on `ubuntu:18.04` and `ubuntu:20.04`, with the following packages being required to be preinstalled before running.
  +```
  +sudo apt-get install git wget tar make abootimg simg2img mount qemu-user-static img2simg unzip fdisk build-essential fakeroot libncurses5-dev ccache bc libfdt-dev
  +```
  +#### Usage
  +```
  +./setup [OPTIONS]
  +
  +-h|--help
  + Print a usage message briefly summarizing the command line options available, then exit.
  +-y|--yes
  + Automatic yes to prompts.
  +--arch
  + Specify the architecture for which the kernel is built.
  + Default: arm64
  +--cross_compile
  + Specify the toolchain for the cross compile.
  + Default: toolchain/bin/aarch64-linux-gnu-
  +--kernel_version
  + Specify the kernel version.
  + Default: 4.9-camera-lt-qcom
  +--kernel_modules_path
  + Specify the kernel modules path.
  + Default: db410c-modules
  +--kernel_repo
  + Specify the repo from where the kernel is cloned.
  + Default: https://github.com/D3Engineering/linux_kernel_qcomlt.git
  +--kernel_branch
  + Specify the branch that will be used from kernel_repo.
  + Default: d3/release/ov5640_4.9.27
  +--kernel_patches
  + Specify the patches that will be applied to kernel_repo.
  + Default: kernel_4_9_27
  +--branch
  + Specify the aditof_sdk branch/tag that will be built.
  + Default: master
  +--image_name
  + Specify the name of the resulting image.
  + Default: dragonboard410c_latest_<sha of HEAD commit from "branch">
  +```
  +#### Troubleshooting
  +1. For the script to work with other `kernel_branch` / `kernel_repo` values make sure to specify the `kernel_patches` which is the folder containing this patches. This folder must be in [the linux patches for dragonboard folder](https://github.com/analogdevicesinc/aditof_sdk/tree/master/sdcard-images-utils/dragonboard410c/linux-patches)
  +2. In case an error occurs while running the script due to a missing package, or something else, before attempting to run again make sure to remove the folder in which the script temporarily works. The folder should be `.temp` and should be at the same level as the `image.sh` script (../aditof_sdk/sdcard-images-utils/dragonboard410c/utils)
  