[docs][PATCH 2/2] ref-manual/variables.rst: Document SPDX_AUTHORS

[Joshua Watt <jpewhacker@gmail.com>]

Document the SPDX_AUTHORS variable. There was some confusion about how
this variable works compared to the other single-agent variables, so
adding explicit documentation that indicates how it diverges is useful.

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
---
 documentation/ref-manual/variables.rst | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index e1d3cd70f..4ec4ce988 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -9499,6 +9499,29 @@ system and gives an overview of their function and contents.
       ``SPDX_IMPORTS``, :term:`SPDX_INVOKED_BY`,
       and :term:`SPDX_ON_BEHALF_OF`.
 
+   :term:`SPDX_AUTHORS`
+      This variable is used to list the authors of the created SPDX data.
+      It works slightly differently than the other agent variables (like
+      :term:`SPDX_IMAGE_SUPPLIER`) in that the base variable provides a list of
+      suffixes which are used to construct the variable prefixes for the
+      created authors. For example::
+
+        SPDX_AUTHORS = "myorg myself"
+        SPDX_AUTHORS_myorg_name = "My Organization"
+        SPDX_AUTHORS_myorg_type = "organization"
+        SPDX_AUTHORS_myself_name = "My Name"
+        SPDX_AUTHORS_myself_type = "Person"
+
+
+      Note that references to other objects can be made using the ``_ref``
+      suffix, for example::
+
+        SPDX_AUTHORS_myself_ref = "SPDX_IMAGE_SUPPLIER"
+
+      And other variables can reference authors by using the correct prefix::
+
+        SPDX_IMAGE_SUPPLIER_ref = "SPDX_AUTHORS_myorg"
+
    :term:`SPDX_CONCLUDED_LICENSE`
       The :term:`SPDX_CONCLUDED_LICENSE` variable allows overriding the
       ``hasConcludedLicense`` object to individual SBOM packages. This can be
-- 
2.55.0