fix wrong [storage backend] in s3 configuration (#161)

Author: christophdb

docs/config/enterprise/S3.md

@@ -30,7 +30,7 @@ SeaTable allows the use of S3 from AWS or any other S3 compatible object storage
 
 ## Use S3 for base snapshots
 
-The storage of base snapshots are configured in `dtable-storage-server.conf`. By default the section `[storage_backend]` contains `type = local`. With this setting, all base snapshots are stored in the folder `/opt/seatable/seatable-data/seatable/storage-data`.
+The storage of base snapshots are configured in `dtable-storage-server.conf`. By default the section `[storage backend]` contains `type = local`. With this setting, all base snapshots are stored in the folder `/opt/seatable/seatable-data/seatable/storage-data`.
 
 Switch the type to `type = s3` to use S3 Object storage. Depending on whether you are using AWS or an S3 compatible service, different configuration options must be used.
 
@@ -39,7 +39,7 @@ Switch the type to `type = s3` to use S3 Object storage. Depending on whether yo
     AWS requires only a few settings. `key_id` and `key` are used to provide S3 authentication. You can find the `key_id` and `key` in the *Security Credentials* section of your AWS account page.
 
     ```
-    [storage_backend]
+    [storage backend]
     type = s3
     bucket = ...
     key_id =
@@ -67,7 +67,7 @@ Switch the type to `type = s3` to use S3 Object storage. Depending on whether yo
     Use the following settings to connect to your S3 compatible storage.
 
     ```
-    [storage_backend]
+    [storage backend]
     type = s3
     bucket = ...
     host = ...