Note build.jobs required other keys
This doesn't have a good error message, we should at least note it.
@@ -445,6 +445,7 @@ See :doc:`/build-customization` for more details.
.. note::
Each key under ``build.jobs`` must be a list of strings.
+ `build.os` and `build.tools` are also required to use `build.jobs`.
:Type: ``dict``
