doc: board: Convert i.MX8MN EVK README to reST

Convert plain text documentation to reStructuredText format and add
it to Sphinx TOC tree. No essential content change.

Signed-off-by: Peng Fan <peng.fan@nxp.com>

board/freescale/imx8mn_evk/README

@@ -1,37 +0,0 @@
-U-Boot for the NXP i.MX8MN EVK board
-
-Quick Start
-===========
-- Build the ARM Trusted firmware binary
-- Get firmware-imx package
-- Build U-Boot
-- Boot
-
-Get and Build the ARM Trusted firmware
-======================================
-Note: srctree is U-Boot source directory
-Get ATF from: https://source.codeaurora.org/external/imx/imx-atf
-branch: imx_4.19.35_1.1.0
-$ make PLAT=imx8mn bl31
-$ cp build/imx8mn/release/bl31.bin $(srctree)
-
-Get the ddr firmware
-=============================
-$ wget https://www.nxp.com/lgfiles/NMG/MAD/YOCTO/firmware-imx-8.5.bin
-$ chmod +x firmware-imx-8.5.bin
-$ ./firmware-imx-8.5
-$ cp firmware-imx-8.5/firmware/ddr/synopsys/ddr4*.bin $(srctree)
-
-Build U-Boot
-============
-$ export CROSS_COMPILE=aarch64-poky-linux-
-$ make imx8mn_ddr4_evk_defconfig
-$ export ATF_LOAD_ADDR=0x960000
-$ make flash.bin
-
-Burn the flash.bin to MicroSD card offset 32KB
-$sudo dd if=flash.bin of=/dev/sd[x] bs=1024 seek=32 conv=notrunc
-
-Boot
-====
-Set Boot switch to SD boot

doc/board/freescale/imx8mn_evk.rst

@@ -0,0 +1,57 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+imx8mn_evk
+==========
+
+U-Boot for the NXP i.MX8MN EVK board
+
+Quick Start
+-----------
+
+- Build the ARM Trusted firmware binary
+- Get firmware-imx package
+- Build U-Boot
+- Boot
+
+Get and Build the ARM Trusted firmware
+--------------------------------------
+
+Note: srctree is U-Boot source directory
+Get ATF from: https://source.codeaurora.org/external/imx/imx-atf
+branch: imx_4.19.35_1.1.0
+
+.. code-block:: bash
+
+   $ make PLAT=imx8mn bl31
+   $ cp build/imx8mn/release/bl31.bin $(srctree)
+
+Get the ddr firmware
+--------------------
+
+.. code-block:: bash
+
+   $ wget https://www.nxp.com/lgfiles/NMG/MAD/YOCTO/firmware-imx-8.5.bin
+   $ chmod +x firmware-imx-8.5.bin
+   $ ./firmware-imx-8.5
+   $ cp firmware-imx-8.5/firmware/ddr/synopsys/ddr4*.bin $(srctree)
+
+Build U-Boot
+------------
+
+.. code-block:: bash
+
+   $ export CROSS_COMPILE=aarch64-poky-linux-
+   $ make imx8mn_ddr4_evk_defconfig
+   $ export ATF_LOAD_ADDR=0x960000
+   $ make flash.bin
+
+Burn the flash.bin to MicroSD card offset 32KB:
+
+.. code-block:: bash
+
+   $sudo dd if=flash.bin of=/dev/sd[x] bs=1024 seek=32 conv=notrunc
+
+Boot
+----
+
+Set Boot switch to SD boot

doc/board/freescale/index.rst

@@ -7,4 +7,5 @@ Freescale
    :maxdepth: 2
 
    b4860qds
+   imx8mn_evk
    imx8mp_evk