docs: tick off Velero 1.16.2

Test backup of gatus and ntfy completed on the new version.

docs/upgrade-k8s-1.33.md

@@ -35,7 +35,7 @@ snapshots after every step. Fresh Velero backup before starting.
 
 - [ ] CloudNativePG 1.25.1 → 1.26 → 1.27 → 1.28.4 (each step restarts the
   single-instance databases)
-- [ ] Velero 1.15.2 → 1.16.x (chart 10.x), plugin-for-aws v1.12
+- [x] Velero 1.15.2 → 1.16.2 (chart 10.1.3), plugin-for-aws v1.12.2
 - [ ] Vault chart 0.28.1 → ≥0.30.1 (vault-k8s 1.7.0)
 - [x] cert-manager 1.15.5 → 1.16.5 → 1.17.4 → 1.18.6 → 1.19.6 → 1.20.4
   (1.18 changes the `rotationPolicy` default to Always)