Update README.md

Author: Cyclenerd

README.md

@@ -66,9 +66,10 @@ Attribute mapping:
 | Attribute              | Claim                                                 |
 |------------------------|-------------------------------------------------------|
 | `google.subject`       | `assertion.sub`                                       |
+| `attribute.sub`        | `assertion.sub`                                       |
 | `attribute.repository` | `assertion.project_path` (not `assertion.repository`) |
 | `attribute.user_login` | `assertion.user_login`                                |
-| `attribute.branch`     | `assertion.ref`                                       |
+| `attribute.ref`        | `assertion.ref`                                       |
 
 <!-- BEGIN_TF_DOCS -->
 ## Providers