[PATCH v2] ref-manual: explain default value used for SUMMARY

Explain that if you do not set a value for the SUMMARY variable in a
recipe file, that will generate a warning and that variable will be
set to a default value from the meta/conf/bitbake.conf file.

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..dc11ea326 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -10350,6 +10350,10 @@ system and gives an overview of their function and contents.
       :term:`DESCRIPTION` variable if :term:`DESCRIPTION` is
       not set in the recipe.

+      If you don't set this variable in your recipe file, you will be warned
+      about that and it will be set to a default value from the
+      :oecore_path:`meta/conf/bitbake.conf` file.
+
    :term:`SVNDIR`
       The directory in which files checked out of a Subversion system are
       stored.