docs: clarify namespacing when using modules.

docs/snakefiles/modularization.rst

@@ -137,9 +137,12 @@ Here, plain paths, HTTP/HTTPS URLs and special markers for code hosting provider
 The second statement, ``use rule * from other_workflow as other_*``, declares all rules of that module to be used in the current one.
 Thereby, the ``as other_*`` at the end renames all those rules with a common prefix.
 This can be handy to avoid rule name conflicts (note that rules from modules can otherwise overwrite rules from your current workflow or other modules).
+
 The module is evaluated in a separate namespace, and only the selected rules are added to the current workflow.
 Non-rule Python statements inside the module are also evaluated in that separate namespace.
 They are available in the module-defining workflow under the name of the module (e.g. here ``other_workflow.myfunction()`` would call the function ``myfunction`` that has been defined in the model, e.g. in ``other_workflow/Snakefile``).
+Also note that this means that any Python variables and functions available in the module-defining namespace will **not** be visible from inside the module.
+However, it is possible to pass information to the module using the ``config`` mechanism described in the following.
 
 It is possible to overwrite the global config dictionary for the module, which is usually filled by the ``configfile`` statement (see :ref:`snakefiles_standard_configuration`):