add migration guide

Author: michaelwittig

docs/migrate-v12.md

@@ -0,0 +1,18 @@
+<iframe src="https://ghbtns.com/github-btn.html?user=widdix&repo=aws-cf-templates&type=star&count=true&size=large" frameborder="0" scrolling="0" width="160px" height="30px"></iframe>
+
+> **New**: [Become a sponsor](https://github.com/sponsors/widdix) via GitHub Sponsors!
+
+# Migrate from v11 to v12
+
+## *
+
+IPv6 support for subnets, public load balancers, and CloudFront. EC2 instances still use IPv4 only by default!
+
+## Deprecation warnings
+
+* `ec2/ec2-auto-recovery`: Template will be removed in v13. Use `ec2/al2-mutable-public` or `ec2/al2-mutable-private` instead. (deprecated since v11)
+* `state/dynamodb`: Parameter `Encryption` will be removed in v13. Use parameter `ParentKmsKeyStack` instead. (deprecated since v11)
+
+## Deprecations
+
+none

mkdocs.yml

@@ -18,6 +18,7 @@ pages:
   - 'WordPress': 'wordpress.md'
 - 'widdix CLI': 'cli.md'
 - 'Migration Guides':
+  - 'Migrate to v12': 'migrate-v12.md'
   - 'Migrate to v11': 'migrate-v11.md'
   - 'Migrate to v10': 'migrate-v10.md'
   - 'Migrate to v9': 'migrate-v9.md'