PyDoc: add 'rtype' field for multiple return values

Ref: !131482

doc/python_api/sphinx_doc_gen.py

@@ -1675,7 +1675,8 @@ def pyrna2sphinx(basepath):
             if len(func.return_values) == 1:
                 write_param("      ", fw, func.return_values[0], is_return=True)
             elif func.return_values:  # Multiple return values.
-                fw("      :return ({:s}):\n".format(", ".join(prop.identifier for prop in func.return_values)))
+                fw("      :return:\n")
+                type_descrs = []
                 for prop in func.return_values:
                     # TODO: pyrna_enum2sphinx for multiple return values,
                     # actually don't think we even use this but still!
@@ -1690,6 +1691,7 @@ def pyrna2sphinx(basepath):
                         collection_id=_BPY_PROP_COLLECTION_ID,
                         enum_descr_override=enum_descr_override,
                     )
+                    type_descrs.append(type_descr)
                     descr = prop.description
                     if not descr:
                         descr = prop.name
@@ -1698,6 +1700,7 @@ def pyrna2sphinx(basepath):
                         prop.identifier,
                         ", ".join((val for val in (descr, type_descr) if val))
                     ))
+                fw("      :rtype: ({:s})\n".format(", ".join(type_descrs)))
 
             write_example_ref("      ", fw, struct_module_name + "." + struct_id + "." + func.identifier)