📖 Add v1.6 -> v1.7 migration doc

docs/book/src/SUMMARY.md

@@ -95,6 +95,7 @@
           - [v1.3 to v1.4](./developer/providers/migrations/v1.3-to-v1.4.md)
           - [v1.4 to v1.5](./developer/providers/migrations/v1.4-to-v1.5.md)
           - [v1.5 to v1.6](./developer/providers/migrations/v1.5-to-v1.6.md)
+          - [v1.6 to v1.7](./developer/providers/migrations/v1.6-to-v1.7.md)
         - [Provider contracts](./developer/providers/contracts.md)
           - [Cluster Infrastructure](./developer/providers/cluster-infrastructure.md)
           - [Machine Infrastructure](./developer/providers/machine-infrastructure.md)

docs/book/src/developer/providers/migrations/v1.6-to-v1.7.md

@@ -0,0 +1,27 @@
+# Cluster API v1.6 compared to v1.7
+
+This document provides an overview over relevant changes between Cluster API v1.6 and v1.7 for
+maintainers of providers and consumers of our Go API.
+
+## Go version
+
+- The Go version used by Cluster API is Go 1.20.x
+
+## Dependencies
+
+**Note**: Only the most relevant dependencies are listed, `k8s.io/` and `ginkgo`/`gomega` dependencies in Cluster API are kept in sync with the versions used by `sigs.k8s.io/controller-runtime`.
+
+
+## Changes by Kind
+
+### Deprecation
+
+### Removals
+
+- API version `v1alpha4` is now completely removed.
+
+### API Changes
+
+### Other
+
+### Suggested changes for providers