Update setup_with_s3.md

Improve description about options.

manual/setup/setup_with_s3.md

@@ -54,14 +54,14 @@ You have to create at least **3** buckets for Seafile, corresponding to the sect
 | Variable | Description |  
 | --- | --- |  
 | `bucket` | Bucket name for commit, fs, and block objects. Make sure it follows [S3 naming rules](https://docs.aws.amazon.com/AmazonS3/latest/userguide/BucketRestrictions.html#bucketnamingrules) (you can refer the notes below the table). |  
-| `key_id` | The `key_id` is required to authenticate you to S3. You can find the `key_id` in the "security credentials" section on your AWS account page. |  
-| `key` | The `key` is required to authenticate you to S3. You can find the `key` in the "security credentials" section on your AWS account page. |  
+| `key_id` | The `key_id` is required to authenticate you to S3. You can find the `key_id` in the "security credentials" section on your AWS account page or from your storage provider. |  
+| `key` | The `key` is required to authenticate you to S3. You can find the `key` in the "security credentials" section on your AWS account page or from your storage provider. |  
 | `use_v4_signature` | There are two versions of authentication protocols that can be used with S3 storage: Version 2 (older, may still be supported by some regions) and Version 4 (current, used by most regions). If you don't set this option, Seafile will use the v2 protocol. It's suggested to use the v4 protocol. |  
 | `use_https` | Use https to connect to S3. It's recommended to use https. |
 | `aws_region` | (**Optional**) If you use the v4 protocol and AWS S3, set this option to the region you chose when you create the buckets. If it's not set and you're using the v4 protocol, Seafile will use `us-east-1` as the default. This option will be ignored if you use the v2 protocol. |
-| `host` | (**Optional**) The endpoint by which you access the storage service. Usually it starts with the region name. It's required to provide the host address, *otherwise Seafile will use AWS's address* (i.e., `s3.us-east-1.amazonaws.com`).|
-| `sse_c_key` | (**Optional**) A string of 32 characters can be generated by `openssl rand -base64 24`.  It's required to use V4 authentication protocol and https if you enable SSE-C. |
-| `path_style_request` | (**Optional**) This option asks Seafile to use URLs like `https://192.168.1.123:8080/bucketname/object` to access objects. In Amazon S3, the default URL format is in virtual host style, such as `https://bucketname.s3.amazonaws.com/object`. But this style relies on advanced DNS server setup. So most self-hosted storage systems only implement the path style format. So we recommend to set this option to true. |
+| `host` | (**Optional**) The endpoint by which you access the storage service. Usually it starts with the region name. It's required to provide the host address if you use storage provider other than AWS, *otherwise Seafile will use AWS's address* (i.e., `s3.us-east-1.amazonaws.com`).|
+| `sse_c_key` | (**Optional**) A string of 32 characters can be generated by `openssl rand -base64 24`. It can be any 32-character long random string. It's required to use V4 authentication protocol and https if you enable SSE-C. |
+| `path_style_request` | (**Optional**) This option asks Seafile to use URLs like `https://192.168.1.123:8080/bucketname/object` to access objects. In Amazon S3, the default URL format is in virtual host style, such as `https://bucketname.s3.amazonaws.com/object`. But this style relies on advanced DNS server setup. So most self-hosted storage systems only implement the path style format. So we recommend to set this option to true for self-hosted storage. |
 
 [1]: <https://docs.aws.amazon.com/AmazonS3/latest/userguide/BucketRestrictions.html#bucketnamingrules> (Replace this placeholder with the actual link to the S3 bucket naming rules documentation if necessary)