Add release notes for v0.221.0

Author: NicholasBlaskey

docs/release_notes/0.221.0.md

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+# Release v0.221.0
+
+## 🎯 Improvements
+
+- added support us-isob-west-1 region (#8602)
+
+## 🐛 Bug Fixes
+
+- Add taints for AL2023 NodeGroups as tolerations for Nvidia device plugin daemonset (#8627)
+
+## 🧰 Maintenance
+
+- Update ec2-info (#8578)
+
+## Acknowledgments
+
+The eksctl maintainers would like to sincerely thank @NicholasBlaskey, @jdwtf and @knottnt.
+