Create CHANGELOG.md (#4101)

Author: shuyama1

CHANGELOG.md

@@ -1,5 +1,21 @@
 ## 4.13.0 (Unreleased)
 
+FEATURES:
+* **New Resource:** `google_apigee_endpoint_attachment` ([#4074](https://github.com/hashicorp/terraform-provider-google-beta/pull/4074))
+* **New Resource:** `google_cloudfunctions2_function` ([#4093](https://github.com/hashicorp/terraform-provider-google-beta/pull/4093))
+* **New Resource:** `google_region_backend_service_iam_*` ([#4088](https://github.com/hashicorp/terraform-provider-google-beta/pull/4088))
+* **New Datasource:** `google_dns_record_set` ([#4085](https://github.com/hashicorp/terraform-provider-google-beta/pull/4085))
+* **New Datasource:** `google_privateca_certificate_authority` ([#4087](https://github.com/hashicorp/terraform-provider-google-beta/pull/4087))
+
+IMPROVEMENTS:
+* compute: added support for `keepalive_interval` to `google_compute_router.bgp` ([#4089](https://github.com/hashicorp/terraform-provider-google-beta/pull/4089))
+* compute: added update support for `google_compute_reservation.share_settings` ([#4092](https://github.com/hashicorp/terraform-provider-google-beta/pull/4092))
+* storagetransfer: added attribute `subject_id` to data source `google_storage_transfer_project_service_account` ([#4073](https://github.com/hashicorp/terraform-provider-google-beta/pull/4073))
+
+BUG FIXES:
+* composer: allow region to be undefined in configuration for `google_composer_environment` ([#4083](https://github.com/hashicorp/terraform-provider-google-beta/pull/4083))
+* container: fixed a bug where `vertical_pod_autoscaling` would cause autopilot clusters to recreate ([#4076](https://github.com/hashicorp/terraform-provider-google-beta/pull/4076))
+
 ## 4.12.0 (February 28, 2022)
 
 NOTE: