Migration guide: GitHub Advanced Security to GitLab Ultimate

What this post added

This post details the migration of GitHub Advanced Security features to GitLab Ultimate, focusing on SAST and Secret Scanning. It provides a feature-by-feature comparison and migration steps, including adding SAST and Secret Detection templates to `.gitlab-ci.yml` and customizing SAST scanners and rulesets. It highlights GitLab Ultimate's broader security capabilities beyond GitHub Advanced Security.