all: release v0.47.0

Change-Id: I6214dee30fe470c923737a73bd7724032fc122fc
Reviewed-on: https://code-review.googlesource.com/c/gocloud/+/46830
Reviewed-by: Noah Dietz <ndietz@google.com>
diff --git a/CHANGES.md b/CHANGES.md
index 9c53bc5..e50e910 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,13 @@
 # Changes
 
+## v0.47.0
+
+This release drops support for Go 1.9 and Go 1.10: we continue to officially
+support Go 1.11, Go 1.12, and Go 1.13.
+
+- Various updates to autogenerated clients.
+- Add cloudbuild/apiv1 client.
+
 ## v0.46.3
 
 This is an empty release that was created solely to aid in storage's module