[PATCH v2] ref-manual: add missing entry for build/tmp/deploy/spdx

There is no entry in the Build Directory section for the directory
build/tmp/deploy/spdx, so add it.

Signed-off-by: Robert P. J. Day <[email protected]>

---

  i'm going with SBOM referring to the entirety of all that SPDX info.

diff --git a/documentation/ref-manual/structure.rst b/documentation/ref-manual/structure.rst
index ff84b250b..0e8674d68 100644
--- a/documentation/ref-manual/structure.rst
+++ b/documentation/ref-manual/structure.rst
@@ -539,6 +539,16 @@ licensing, see the
 ":ref:`dev-manual/licenses:maintaining open source license compliance during your product's lifecycle`"
 section in the Yocto Project Development Tasks Manual.

+.. _structure-build-tmp-deploy-spdx:
+
+``build/tmp/deploy/spdx/``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This directory contains a Software Bill of Materials (:term:`SBOM`) in
+:term:`SPDX` format, as explained in detail in the
+":ref:`dev-manual/sbom:creating a software bill of materials`"
+section of the Yocto Project Development Tasks Manual.
+
 .. _structure-build-tmp-deploy-images:

 ``build/tmp/deploy/images/``