Docs: add notes on populating bpy.app.driver_namespace

Address issues raised by #114155.

Also fix sphinx documentation generation using incorrect identifiers
when looking up references from PyStruct types
(was looking for `bpy.app.bpy.app.driver_namespace.py`).

doc/python_api/examples/bpy.app.driver_namespace.py

@@ -0,0 +1,19 @@
+"""
+File Loading & Order of Initialization
+   Since drivers are evaluated immediately after loading a blend-file,
+   using ``--python`` to populate name-space often fails to achieve the desired goal because the initial evaluation
+   will lookup a function that doesn't exist yet, marking the driver as invalid - preventing further evaluation.
+
+   Populating the driver name-space before the blend-file loads also doesn't work
+   since opening a file clears the name-space.
+
+   The driver name-space should be populated for newly loaded files using text-block registration.
+
+   Text blocks may be marked to execute on startup from the text editor *Text -> Register*.
+   Scripts that are registered will execute after a blend-file loads & before driver evaluation.
+
+   It's also possible to use run a script via the ``--python`` command line argument, before the blend file.
+   This can register a load-post handler (:mod:`bpy.app.handlers.load_post`) that initialized the name-space.
+   While this works for background tasks it has the downside that opening the file from the file selector
+   won't setup the name-space.
+"""

doc/python_api/sphinx_doc_gen.py

@@ -986,9 +986,21 @@ def pymodule2sphinx(basepath, module_name, module, title, module_all_extra):
         # `type_name` is only used for examples and messages:
         # `<class 'bpy.app.handlers'>` -> `bpy.app.handlers`.
         type_name = str(type(module)).strip("<>").split(" ", 1)[-1][1:-1]
+
+        # The type typically contains the module in the case of PyStruct's (defined by Blender).
+        # Assign a temporary module name: `module_name_split`.
+        if module_name == type_name:
+            assert "." in module_name
+            module_name_split, type_name = module_name.rpartition(".")[0::2]
+        elif type_name.startswith(module_name + "."):
+            type_name = type_name.removeprefix(module_name + ".")
+        else:
+            module_name_split = module_name
+
         if type(descr) == types.GetSetDescriptorType:
-            py_descr2sphinx("", fw, descr, module_name, type_name, key)
+            py_descr2sphinx("", fw, descr, module_name_split, type_name, key)
             attribute_set.add(key)
+        del module_name_split
     descr_sorted = []
     for key, descr in sorted(type(module).__dict__.items()):
         if key.startswith("__"):