[bitnami/postgresql] add warning regarding setting the password (#10881)

* Add warning related to setting password

Signed-off-by: Denis Palnitsky <palnitsky@gmail.com>
Co-authored-by: Carlos Rodríguez Hernández <carlosrh@vmware.com>

bitnami/postgresql/Chart.yaml

@@ -26,4 +26,4 @@ name: postgresql
 sources:
   - https://github.com/bitnami/bitnami-docker-postgresql
   - https://www.postgresql.org/
-version: 11.6.12
+version: 11.6.13

bitnami/postgresql/README.md

@@ -465,6 +465,8 @@ The above command sets the PostgreSQL `postgres` account password to `secretpass
 
 > NOTE: Once this chart is deployed, it is not possible to change the application's access credentials, such as usernames or passwords, using Helm. To change these application credentials after deployment, delete any persistent volumes (PVs) used by the chart and re-deploy it, or use the application's built-in administrative tools if available.
 
+> **Warning** Setting a password will be ignored on new installation in case when previous Posgresql release was deleted through the helm command. In that case, old PVC will have an old password, and setting it through helm won't take effect. Deleting persistent volumes (PVs) will solve the issue. Refer to [issue 2061](https://github.com/bitnami/charts/issues/2061) for more details  
+
 Alternatively, a YAML file that specifies the values for the parameters can be provided while installing the chart. For example,
 
 ```bash
@@ -669,4 +671,4 @@ Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
-limitations under the License.
+limitations under the License.