docs: how to import volumes

docs/kubernetes/how-to-import-volumes.md

@@ -0,0 +1,41 @@
+# How to import volumes
+
+This guide explains how to import an existing Hetzner volume into your Kubernetes cluster with the csi-driver installed.
+
+1. Detach your volume by running `hcloud volume detach <volume-name>`
+2. Find the ID of your volume by running `hcloud volume list`
+3. Create a new PersistentVolume and insert the volume ID into the `volumeHandle`
+
+```yaml
+apiVersion: v1
+kind: PersistentVolume
+metadata:
+  name: imported-data
+spec:
+  storageClassName: hcloud-volumes
+  capacity:
+    storage: 10Gi
+  accessModes:
+    - ReadWriteOnce
+  csi:
+    fsType: ext4
+    driver: csi.hetzner.cloud
+    volumeHandle: "<VOLUME-ID>"
+```
+
+4. Create a new PersistentVolumeClaim and link it to the PersistentVolume via `volumeName`
+
+```yaml
+kind: PersistentVolumeClaim
+apiVersion: v1
+metadata:
+  name: imported-data
+spec:
+  storageClassName: hcloud-volumes
+  volumeName: imported-data # <-- reference PV name
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 10Gi
+```