[test_operator] Automatic sync of README.md

This commit will ensure to have the proper auto-sync of README.md with the defaults/main.yml file and also added the post-commit file so whenever someone commits in the defaults/main.yml file the script can be auto-run

Ticket: OSPRH-19423

This PR openstack-k8s-operators#3327 is closed since I am not able to reopen the PR

Signing off: Saurabh Agarwal <sauragar@redhat.com>

Author: sauragar