doc: board: kontron: sl28: Reduce section levels and change title

In order to add other Kontron boards to the docs alongside the existing sl28 board,
we need to reduce the levels of the sections and change the title.

Cc: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Acked-by: Michael Walle <michael@walle.cc>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>

doc/board/kontron/sl28.rst

@@ -1,17 +1,17 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-Summary
-=======
+Kontron SMARC-sAL28
+===================
 
 The Kontron SMARC-sAL28 board is a TSN-enabled dual-core ARM A72
 processor module with an on-chip 6-port TSN switch and a 3D GPU.
 
 
 Quickstart
-==========
+----------
 
 Compile U-Boot
---------------
+^^^^^^^^^^^^^^
 
 Configure and compile the binary::
 
@@ -21,7 +21,7 @@ Configure and compile the binary::
 Copy u-boot.rom to a TFTP server.
 
 Install the bootloader on the board
------------------------------------
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 Please note, this bootloader doesn't support the builtin watchdog (yet),
 therefore you have to disable it, see below. Otherwise you'll end up in
@@ -36,7 +36,7 @@ disabled the builtin watchdog you might have to manually enter failsafe
 mode by asserting the ``FORCE_RECOV#`` line during board reset.
 
 Disable the builtin watchdog
-----------------------------
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 - boot into the failsafe bootloader, either by asserting the
   ``FORCE_RECOV#`` line or if you still have the original bootloader
@@ -53,7 +53,7 @@ Disable the builtin watchdog
 
 
 Useful I2C tricks
-=================
+-----------------
 
 The board has a board management controller which is not supported in
 u-boot (yet). But you can use the i2c command to access it.
@@ -68,7 +68,7 @@ u-boot (yet). But you can use the i2c command to access it.
 
 
 Non-volatile Board Configuration Bits
-=====================================
+-------------------------------------
 
 The board has 16 configuration bits which are stored in the CPLD and are
 non-volatile. These can be changed by the `sl28 nvm` command.
@@ -98,21 +98,21 @@ Please note, that if the board is in failsafe mode, the bits will have the
 factory defaults, ie. all bits are off.
 
 Power-On Inhibit
-----------------
+^^^^^^^^^^^^^^^^
 
 If this is set, the board doesn't automatically turn on when power is
 applied. Instead, the user has to either toggle the ``PWR_BTN#`` line or
 use any other wake-up source such as RTC alarm or Wake-on-LAN.
 
 eMMC Boot
----------
+^^^^^^^^^
 
 If this is set, the RCW will be fetched from the on-board eMMC at offset
 1MiB. For further details, have a look at the `Reset Configuration Word
 Documentation`_.
 
 Watchdog
---------
+^^^^^^^^
 
 By default, the CPLD watchdog is enabled in failsafe mode. Using bits 2 and
 3, the user can change its mode or disable it altogether.
@@ -127,21 +127,21 @@ Bit 2  Bit 3  Description
 =====  =====  ===============================
 
 Clock Generator Select
-----------------------
+^^^^^^^^^^^^^^^^^^^^^^
 
 The board is prepared to supply different SerDes clock speeds. But for now,
 only setting 0 is supported, otherwise the CPU will hang because the PLL
 will not lock.
 
 Clock Output Disable And Keep Devices In Reset
-----------------------------------------------
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 To safe power, the user might disable different devices and clock output of
 the board. It is not supported to disable the "CPU SerDes clock #2" for
 now, otherwise the CPU will hang because the PLL will not lock.
 
 Automatic reset of the onboard PHYs
------------------------------------
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 By default, there is no hardware reset of the onboard PHY. This is because
 for Wake-on-LAN, some registers have to retain their values. If you don't
@@ -151,7 +151,7 @@ power-on reset.
 
 
 Further documentation
-=====================
+---------------------
 
 - `Vendor Documentation`_
 - `Reset Configuration Word Documentation`_