Documentation: trivial typo fix strcut/struct

Change-Id: I5e7d8e8a95e5bef23307eb50456a89e0e23c445a
Signed-off-by: Marty E. Plummer <hanetzer@startmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36299
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

Documentation/lib/flashmap.md

@@ -17,7 +17,7 @@ something else) should have its own Flashmap section, and everything else should
 normally go into CBFS.
 
 The Flashmap itself starts with a header `struct fmap` and followed by a list of
-section descriptions in `strcut fmap_area`.
+section descriptions in `struct fmap_area`.
 
 ### Header
 The header `struct fmap` has following fields: