Initial readme.md file

Signed-off-by: Rabeeh Khoury <rabeeh@solid-run.com>

README.md

+# SolidRun's LX2160A COM express type 7 build scripts
+
+## Introduction
+Main intention of this repository is to provide build scripts that are easy to handle than NXP's flexbuild build environment.
+They are used in SolidRun quickly build images for development where those images can be SD or SPI booted or network TFTP (kernel) or used for root NFS
+
+The sources are pulled from NXP's codeaurora repository and patched after being clone using the patches in the patches/ directory
+
+## Build
+Simply running ./runme.sh will check for required tools, clone and build images and place results in images/ directory.
+
+By default the script will create an image bootable from SD (ready to use .img file) with DDR4 SO-DIMMs 3200Mtps, SERDES configuration 8/5/2 (SERDES1 = 8, SERDES2 = 5, SERDES = 2) and u-boot as boot loader.
+Following are the environment variables that can be modified -
+Selecting boot device - *BOOT=sd,xspi*
+Selecting DDR4 SO-DIMM speed - *DDR_SPEED=2400,2600,2900,3200*
+Selecting SERDES configuration - *SERDES=SD1_SD2_SD3*
+Selecting boot loader - *BOOT_LOADER=u-boot,uefi*
+
+Examples - 
+`./runme.sh` will generate *images/lx2160acex7_2000_700_3200_8_5_2_sd.img*
+`BOOT=xspi ./runme` will generate *images/lx2160acex7_2000_700_3200_8_5_2_xspi.img*
+
+## Deploying
+For SD card bootable images, plug in a micro SD into your machine and run the following, where sdX is the location of the SD card got probed into your machine -
+`sudo dd if=images/lx2160acex7_2000_700_3200_8_5_2_sd.img of=/dev/sdX`