doc: correct HiFive Unmatched boot description
Main U-Boot is loaded by sector number, not by partition GUID type.
Fixes: 70415e1e528d ("board: sifive: add HiFive Unmatched board support")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/doc/board/sifive/unmatched.rst b/doc/board/sifive/unmatched.rst
index a994422..de2aab5 100644
--- a/doc/board/sifive/unmatched.rst
+++ b/doc/board/sifive/unmatched.rst
@@ -56,8 +56,10 @@
ZSBL loads the U-Boot SPL (u-boot-spl.bin) from a partition with GUID type
5B193300-FC78-40CD-8002-E86C45580B47
-U-Boot SPL expects u-boot.itb from a partition with GUID
-type 2E54B353-1271-4842-806F-E436D6AF6985
+With the default configuration U-Boot SPL expects u-boot.itb starting at sector
+2082 (CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0x822). It is recommended to use a
+partition with type GUID 2E54B353-1271-4842-806F-E436D6AF6985 for storing
+main U-Boot.
u-boot.itb is a combination of fw_dynamic.bin, u-boot-nodtb.bin and
device tree blob (hifive-unmatched-a00.dtb)