Improve documentation with link to API storage class references

exporter/awss3exporter/README.md

@@ -32,7 +32,7 @@ The following exporter configuration parameters are supported.
 | `encoding_file_extension` | file format extension suffix when using the `encoding` configuration option. May be left empty for no suffix to be appended.               |             |
 | `endpoint`            | (REST API endpoint) overrides the endpoint used by the exporter instead of constructing it from `region` and `s3_bucket`                                       |             |
 | `s3_force_path_style` | [set this to `true` to force the request to use path-style addressing](http://docs.aws.amazon.com/AmazonS3/latest/dev/VirtualHosting.html) | false       |
-| `storage_class`         | S3 storageclass | STANDARD
+| `storage_class`         | [S3 storageclass](https://docs.aws.amazon.com/AmazonS3/latest/userguide/sc-howtoset.html) | STANDARD , STANDARD_IA , ONEZONE_IA ,  GLACIER , EXPRESS_ONEZONE, GLACIER_IR,DEEP_ARCHIVE,REDUCED_REDUNDANCY
 | `disable_ssl`         | set this to `true` to disable SSL when sending requests                                                                                    | false       |
 | `compression`         | should the file be compressed                                                                                                              | none        |