fix(AIP-164): Expunge supports resources in CREATING state (#1618)

Author: wenmh-coder

aip/general/0164.md

@@ -100,10 +100,10 @@ rpc UndeleteBook(UndeleteBookRequest) returns (google.longrunning.Operation) {
 
 ### Expunge
 
-Resources that support soft delete **may** provide an `Expunge` custom method to 
-allow users to trigger immediate permanent deletion of a ready or soft-deleted
-resource. This method can operate on resources that are currently in a ready or 
-soft-deleted state (e.g., `delete_time` is set).
+Resources that support soft delete **may** provide an `Expunge` custom method to
+allow users to trigger immediate permanent deletion of a resource. This method can
+operate on resources that are currently in a `CREATING`, `READY` or `SOFT_DELETED`
+state (e.g., `delete_time` is set).
 
 ```proto
 // Permanently deletes a soft-deleted Book.