[PATCH] ref-manual: add more explanation to glossary variable LICENSE

Add the following to the variable glossary LICENSE entry:

  - it is a required variable in an OE recipe
  - it must be accompanied by LIC_FILES_CHKSUM, except in the
    case where LICENSE = "CLOSED"

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

---

diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index df3666f1c..3558ccf2d 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -5871,7 +5871,8 @@ system and gives an overview of their function and contents.
       section in the Yocto Project Development Tasks Manual.

    :term:`LICENSE`
-      The list of source licenses for the recipe. Follow these rules:
+      This is a required field in an Openembedded recipe file, and should
+      contain a list of source licenses for the recipe. Follow these rules:

       -  Do not use spaces within individual license names.

@@ -5911,6 +5912,12 @@ system and gives an overview of their function and contents.
          LICENSE:${PN} = "GPL-2.0.only"
          LICENSE:${PN}-doc = "GFDL-1.2"

+      .. note::
+
+         A recipe's :term:`LICENSE` value must be accompanied by an associated
+         :term:`LIC_FILES_CHKSUM` value, except in the special case where
+         the :term:`LICENSE` value is set to "CLOSED".
+
    :term:`LICENSE_CREATE_PACKAGE`
       Setting :term:`LICENSE_CREATE_PACKAGE` to "1" causes the OpenEmbedded
       build system to create an extra package (i.e.