add readme for python templates

Author: marceljk

templates/python/README.md

@@ -0,0 +1,14 @@
+# Python templates
+
+This folder contains only our customized python templates. Beside these customized templates,
+the original templates of openapi-generator for python are used. These can be found in the 
+official GitHub repo of the [openapi-generator](https://github.com/OpenAPITools/openapi-generator/tree/v7.13.0/modules/openapi-generator/src/main/resources/python).
+
+If you need to change something in the Python Generator, try always first to add
+[user-defined templates](https://openapi-generator.tech/docs/customization#user-defined-templates),
+instead of overwritten existing templates. These ensure an easier upgrade process, to newer
+versions of the openapi-generator.
+
+If it's required to customize the original templates, you can copy them into this directory.  
+Try to minimize the customization as much as possible, to ensure, that we can easily upgrade
+to newer versions in the future.