docs/flashmap: state the endianness of FMAP

Signed-off-by: Krystian Hebel <krystian.hebel@3mdeb.com>
Change-Id: Idf6d46ed262b18c176d69352e333c56f4fdff66a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55041
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/Documentation/lib/flashmap.md b/Documentation/lib/flashmap.md
index d3d8bbf..68d0ab5 100644
--- a/Documentation/lib/flashmap.md
+++ b/Documentation/lib/flashmap.md
@@ -17,7 +17,8 @@
 normally go into CBFS.
 
 The Flashmap itself starts with a header `struct fmap` and followed by a list of
-section descriptions in `struct fmap_area`.
+section descriptions in `struct fmap_area`. All fields in those structures are
+in little endian format.
 
 ### Header
 The header `struct fmap` has following fields: