[PATCH] Documentation/kbuild: Document the kconfig choice default value

[Robert Richter]

Document how choice defaults are determined:

Default of a choice is its first visible choice element [1]. Choice
elements do not support default attributes. [2]

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/kconfig/symbol.c?h=v5.14-rc1#n245
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/kconfig/menu.c?h=v5.14-rc1#n494

Signed-off-by: Robert Richter <rrichter@xxxxxxx>
---
 Documentation/kbuild/kconfig-language.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/kbuild/kconfig-language.rst b/Documentation/kbuild/kconfig-language.rst
index 98c24183d8c3..e4d3463594e1 100644
--- a/Documentation/kbuild/kconfig-language.rst
+++ b/Documentation/kbuild/kconfig-language.rst
@@ -417,6 +417,9 @@ definitions of that choice. If a [symbol] is associated to the choice,
 then you may define the same choice (i.e. with the same entries) in another
 place.
 
+The default value of a choice is set to the first visible choice element.
+Choice elements do not support the default attribute like menu entries do.
+
 comment::
 
 	"comment" <prompt>
-- 
2.29.2