Update README to clarify MINIO_POLICY_PATH description, specifying the option to provide a custom JSON file by mounting to the /policies directory.

Author: jaydrogers

README.md

@@ -61,7 +61,7 @@ The following environment variables can be used to customize the MinIO user init
 | `MINIO_ALIAS` | Alias for the MinIO server | `minio` |
 | `MINIO_USER_BUCKET_PERMISSIONS` | Comma-separated list of bucket permissions | `s3:ListBucket,s3:GetBucketLocation,s3:ListBucketMultipartUploads` |
 | `MINIO_USER_OBJECT_PERMISSIONS` | Comma-separated list of object permissions | `s3:PutObject,s3:GetObject,s3:DeleteObject,s3:ListMultipartUploadParts,s3:AbortMultipartUpload` |
-| `MINIO_POLICY_PATH` | Path to store the policy file. This file will be created if it doesn't exist. | `/policies/readwrite-bucket.json` |
+| `MINIO_POLICY_PATH` | Path to the policy file. This file will be created if it doesn't exist or you can provide your own JSON by mounting to the `/policies` directory. | `/policies/readwrite-bucket.json` |
 | `DEBUG` | Enable debug mode | `false` |
 | `SLEEP` | Keep container running after initialization | `true` |