Making CI/CD easier with GitLab

What this post added

This post introduces the fundamental concepts of GitLab CI/CD, including `.gitlab-ci.yml` structure, jobs, stages, variables, and flow control mechanisms (`only`, `except`, `when`). It also demonstrates how to create reusable CI/CD templates using YAML anchors and references to manage deployments across different environments (production, staging) and regions, emphasizing DRY principles and variable-driven configuration.