doc: describe MSEL settings for booting from SD card

unmatched.rst describes booting from SD card or from SPI. But only for
booting from SPI the boot selection settings are described.

Add the missing information.

Fix a typo 'uSD'.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

diff --git a/doc/board/sifive/unmatched.rst b/doc/board/sifive/unmatched.rst
index b52a1f690cc669b4244d8fb9cca89cdc1f7b0237..24a889991c457ca02c06a44102020ac44096231f 100644 (file)
--- a/doc/board/sifive/unmatched.rst
+++ b/doc/board/sifive/unmatched.rst
@@ -20,8 +20,11 @@ The support for following drivers are already enabled:
 4. SiFive SPI Driver.
 5. MMC SPI Driver for MMC/SD support.
 
-Booting from uSD using U-Boot SPL
----------------------------------
+Booting from micro SD card using U-Boot SPL
+-------------------------------------------
+
+Booting from an SD card requires that the boot mode selection DIP switches
+MSEL[3:0] are set to 1011.
 
 Building
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