Day 6 - Fix code block formatting and syncWindows manifest in Introduction to ArgoCD

[sonu7089]

Fixes missing code block language identifiers and an inaccurate syncWindows YAML snippet in content/posts/introduction-to-argocd.md as part of the Hacktoberfest Day 6 challenge.

Details

• What I found: 7 ASCII diagram and directory tree code blocks in content/posts/introduction-to-argocd.md were missing the ext language identifier, and the syncWindows example placed syncWindows under an Application spec with syncPolicy instead of an AppProject resource (and used a range 9-17 alongside duration: 8h).
• Where I found it: https://devops-daily.com/posts/introduction-to-argocd (content/posts/introduction-to-argocd.md)
• What I fixed: Added ext language identifiers to all 7 unlabeled fenced blocks and updated the syncWindows YAML snippet to use kind: AppProject with a valid start-time cron schedule (