Add high-demand skills and fix broken skill links

infrastructure/cloud-aws/aws-cost-optimization/SKILL.md

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+---
+name: aws-cost-optimization
+description: Reduce AWS spend with rightsizing, autoscaling, commitment planning, and storage lifecycle policies. Use when running FinOps reviews, lowering cloud bills, or improving cost-per-request metrics.
+license: MIT
+metadata:
+  author: devops-skills
+  version: "1.0"
+---
+
+# AWS Cost Optimization
+
+Apply practical FinOps controls without sacrificing reliability.
+
+## When to Use This Skill
+
+Use this skill when:
+- Monthly AWS cost spikes unexpectedly
+- Preparing cost reviews with engineering and finance
+- Rightsizing EC2, RDS, and EKS workloads
+- Choosing Savings Plans or Reserved Instances
+
+## Cost Review Workflow
+
+1. Tag resources by team, service, and environment.
+2. Use Cost Explorer and CUR to identify top spend drivers.
+3. Rightsize underutilized compute and storage.
+4. Apply commitment discounts for stable baseline usage.
+5. Set budgets, anomaly alerts, and KPI reporting.
+
+## High-Impact Actions
+
+- Move bursty non-prod compute to Spot where safe.
+- Configure S3 lifecycle rules for infrequent access and archive tiers.
+- Reduce NAT Gateway and inter-AZ data transfer surprises.
+- Schedule dev/test shutdown windows outside business hours.
+- Tune log retention (CloudWatch, OpenSearch) to policy requirements.
+
+## Useful Commands
+
+```bash
+# Cost Explorer rightsizing recommendations (example)
+aws ce get-rightsizing-recommendation \
+  --service "AmazonEC2" \
+  --configuration file://rightsizing-config.json
+
+# List unattached EBS volumes
+aws ec2 describe-volumes --filters Name=status,Values=available
+
+# Retrieve budget alerts
+aws budgets describe-budgets --account-id 123456789012
+```
+
+## Related Skills
+
+- [aws-ec2](../aws-ec2/) - EC2 operations and sizing
+- [aws-s3](../aws-s3/) - S3 storage and lifecycle controls
+- [terraform-aws](../terraform-aws/) - Codifying cost guardrails