Create 1.3.0-upgrade-guide.html.markdown (#682)

Create an upgrade guide for v1.3.0

Author: themantissa

website/docs/guides/1.3.0-upgrade-guide.html.markdown

@@ -0,0 +1,29 @@
+---
+layout: "mongodbatlas"
+page_title: "MongoDB Atlas Provider 1.3.0: Upgrade and Information Guide"
+sidebar_current: "docs-mongodbatlas-guides-130-upgrade-guide"
+description: |-
+MongoDB Atlas Provider 1.3.0: Upgrade and Information Guide
+---
+
+# MongoDB Atlas Provider 1.3.0: Upgrade and Information Guide
+
+The Terraform MongoDB Atlas Provider version 1.3.0 has a number of new and exciting features and changes.
+
+New Features:
+
+* Now supports Cloud Backup Snapshot Export, both [`cloud_backup_snapshot_export_bucket`](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/resources/cloud_backup_snapshot_export_bucket) and [`cloud_backup_snapshot_export_job`](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/resources/cloud_backup_snapshot_export_job)
+* You can now configure advanced configuration options with [`advanced_cluster`](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/resources/advanced_cluster)
+
+Changes:
+
+1.3.0 also includes general improvements and bug fixes. See the [CHANGELOG](https://github.com/mongodb/terraform-provider-mongodbatlas/blob/master/CHANGELOG.md) for more specific information.
+
+### Helpful Links
+
+* [Report bugs](https://github.com/mongodb/terraform-provider-mongodbatlas/issues)
+
+* [Request Features](https://feedback.mongodb.com/forums/924145-atlas?category_id=370723)
+
+* [Contact Support](https://docs.atlas.mongodb.com/support/) covered by MongoDB Atlas support plans, Developer and above.
+