testing lint step - continuous integration

Author: twfksh

README.md

@@ -2,4 +2,6 @@
 
 1. create a python virtualenv `python -m venv ~/.venv` or `virtualenv ~/.venv`
 2. create empty files `Makefile`, `requirements.txt`, `main.py`, `Dockerfile`, `lib/__init__.py`
-3. populate `Makefile`
+3. populate `Makefile`
+4. setup continuous integration, i.e. check for issues like lint errors
+   ![testing_lint_step](https://github.com/user-attachments/assets/183073e5-18f0-49c7-8996-f9c4190c1a1d)