docs: add changelog 3.16.1, update upgrade instruction

docs/changelog/bytebase-3-16-1.mdx

@@ -0,0 +1,33 @@
+---
+title: Bytebase 3.16.1 - Mar 26, 2026
+author: Adela
+updated_at: 2026/03/26 18:00:00
+description: 'Improvements and Bug Fixes'
+
+---
+
+import InstallUpgrade from '/snippets/install/install-upgrade.mdx';
+
+## 🎄 Enhancements
+
+- Change issue approval status label from "Done" to "Approved" for clarity.
+
+- Add fast-follow refresh mode so rollout status updates more quickly after user actions.
+
+- **CosmosDB** — Support more query syntax in SQL editor.
+
+## 🐞 Bug Fixes
+
+- Fix internal error after login caused by InputOtp null check regression.
+
+- Fix popover dismissing when interacting with label selector during plan/issue creation.
+
+- Fix invalid issue type filter in Export Center.
+
+- Fix webhook detail page broken by UUID resource_id migration.
+
+- Harden 3.16 upgrade migration scripts to be idempotent and handle edge cases.
+
+- **PolarDB** — Fix schema dump incorrectly including pg_bitmapindex system schema.
+
+<InstallUpgrade />

docs/docs.json

@@ -368,6 +368,7 @@
       {
         "tab": "Changelog",
         "pages": [
+          "changelog/bytebase-3-16-1",
           "changelog/bytebase-3-16-0",
           "changelog/bytebase-3-15-1",
           "changelog/bytebase-3-15-0",

docs/snippets/install/install-upgrade.mdx

@@ -8,4 +8,4 @@ title: Install and Upgrade
 
 - [Upgrade](/get-started/self-host/upgrade)
 
-_Warning 1): Bytebase does not support in-place downgrade. Make sure to back up your metadata before upgrading. 2) Never run multiple containers on the same data directory. Stop and remove the old one first to avoid corruption._
+_Before upgrading: 1) Back up the [metadata](https://www.bytebase.com/docs/administration/back-up-restore-metadata/) — in-place downgrade is not supported. 2) Do not run multiple containers on the same data directory. 3) Terraform users: upgrade Bytebase server first, then apply the new Terraform config._