fix typo

Signed-off-by: silenceshell <me@ieevee.com>

contrib/helm/harbor/README.md

@@ -189,4 +189,23 @@ The following tables lists the configurable parameters of the Harbor chart and t
 | `notary.affinity` | Node/Pod affinities | `{}` |
 
 ## Persistence
-TBD
+
+You need to create `StorageClass` before you can persist data in persistent volume.
+
+To create a `StorageClass`, set the following value in `values.yaml`:
+
+```yaml
+persistence:
+  enabled: true
+
+```
+
+Four PVCs will be created automatically:
+- adminserver-config
+- chartmuseum-data
+- database-data
+- registry-data
+
+All the created PVCs need to be removed manually after Helm deletes the Chart. 
+
+When running a cluster without persistence, this Chart uses `emptyDir` as the temporary volumes. Data does not survive the termination of a pod.

docs/migration_guide.md

@@ -49,7 +49,7 @@ When upgrading your existing Habor instance to a newer version, you may need to
     docker run -it --rm -e DB_USR=root -e DB_PWD={db_pwd} -v ${harbor_db_path}:/var/lib/mysql -v ${harbor_cfg}:/harbor-migration/harbor-cfg/harbor.cfg -v ${backup_path}:/harbor-migration/backup goharbor/harbor-migrator:[tag] backup
     ```
 
-    **NOTE:** By default, the migrator handles the backup for DB or CFG. If you want to backup DB or CFG only, refer to the following commands.
+    **NOTE:** By default, the migrator handles the backup for DB and CFG. If you want to backup DB or CFG only, refer to the following commands.
     
     ```
     docker run -it --rm -e DB_USR=root -e DB_PWD={db_pwd} -v ${harbor_db_path}:/var/lib/mysql -v ${backup_path}:/harbor-migration/backup goharbor/harbor-migrator:[tag] --db backup