docs/vmrestore: link to auth examples in vmbackup

vmbackup, vmrestore and vmbackupmanager use the same libs
for integrations with object storage. That means the auth can be configured
in the same way for all of them. So the docs should have either identical
config section for all 3 components, or we should cross-link to one source of truth.

This change removes incomplete auth options from vmrestore docs and adds link
to complete auth options in vmbackup instead.

Signed-off-by: hagen1778 <roman@victoriametrics.com>
(cherry picked from commit b29154a497)

docs/vmrestore.md

@@ -49,47 +49,10 @@ i.e. the end result would be similar to [rsync --delete](https://askubuntu.com/q
 
 ## Advanced usage
 
-* Obtaining credentials from a file.
+Please, see [vmbackup docs](https://docs.victoriametrics.com/vmbackup/#advanced-usage) for examples of authentication 
+with different storage types.
 
-  Add flag `-credsFilePath=/etc/credentials` with following content:
+Run `vmrestore -help` in order to see all the available options:
-
-    for s3 (aws, minio or other s3 compatible storages):
-
-     ```sh
-     [default]
-     aws_access_key_id=theaccesskey
-     aws_secret_access_key=thesecretaccesskeyvalue
-    ```
-
-    for gce cloud storage:
-
-    ```json
-    {
-           "type": "service_account",
-           "project_id": "project-id",
-           "private_key_id": "key-id",
-           "private_key": "-----BEGIN PRIVATE KEY-----\nprivate-key\n-----END PRIVATE KEY-----\n",
-           "client_email": "service-account-email",
-           "client_id": "client-id",
-           "auth_uri": "https://accounts.google.com/o/oauth2/auth",
-           "token_uri": "https://accounts.google.com/o/oauth2/token",
-           "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
-           "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/service-account-email"
-    }
-    ```
-
-* Usage with s3 custom url endpoint.  It is possible to use `vmrestore` with s3 api compatible storages, like  minio, cloudian and other.
-  You have to add custom url endpoint with a flag:
-
-```sh
-  # for minio:
-  -customS3Endpoint=http://localhost:9000
-
-  # for aws gov region
-  -customS3Endpoint=https://s3-fips.us-gov-west-1.amazonaws.com
-```
-
-* Run `vmrestore -help` in order to see all the available options:
 
 ```sh
   -concurrency int