board: gateworks: venice: move README to RST

Move board/gateworks/venice/README to RST documentation.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>

board/gateworks/venice/MAINTAINERS

@@ -3,5 +3,6 @@ M:	Tim Harvey <tharvey@gateworks.com>
 S:	Maintained
 F:	arch/arm/dts/imx8m*-venice*
 F:	board/gateworks/venice/
+F:	doc/board/gateworks/*venice*
 F:	include/configs/imx8m*_venice.h
 F:	configs/imx8m*_venice_defconfig

board/gateworks/venice/README

@@ -1,35 +0,0 @@
-U-Boot for the Gateworks i.MX8M Mini Venice Development Kit boards
-
-Quick Start
-===========
-- Build the ARM Trusted firmware binary
-- Get ddr firmware
-- Build U-Boot
-- Flash to eMMC
-- Boot
-
-Get and Build the ARM Trusted firmware
-======================================
-$ git clone https://github.com/nxp-imx/imx-atf
-$ git checkout imx_5.4.47_2.2.0
-$ make PLAT=imx8mm CROSS_COMPILE=aarch64-linux-gnu- bl31
-$ cp build/imx8mm/release/bl31.bin .
-
-Get the DDR Firmware
-====================
-$ wget https://www.nxp.com/lgfiles/NMG/MAD/YOCTO/firmware-imx-8.9.bin
-$ chmod +x firmware-imx-8.9.bin
-$ ./firmware-imx-8.9.bin
-$ cp firmware-imx-8.9/firmware/ddr/synopsys/lpddr4*.bin .
-
-Build U-Boot
-============
-$ make imx8mm_venice_defconfig
-$ make CROSS_COMPILE=aarch64-linux-gnu-
-
-Update eMMC
-===========
-=> tftpboot $loadaddr flash.bin
-=> setexpr blkcnt $filesize + 0x1ff && setexpr blkcnt $blkcnt / 0x200
-=> mmc dev 2 && mmc write $loadaddr 0x42 $blkcnt # for IMX8MM
-=> mmc dev 2 && mmc write $loadaddr 0x40 $blkcnt # for IMX8MN