Mention indirect descriptor support in README.

Author: qwandor

README.md

@@ -32,7 +32,7 @@ VirtIO guest drivers in Rust. For **no_std** environment.
 
 | Feature flag                 | Supported |                                         |
 | ---------------------------- | --------- | --------------------------------------- |
-| `VIRTIO_F_INDIRECT_DESC`     | ❌        | Indirect descriptors                    |
+| `VIRTIO_F_INDIRECT_DESC`     | ✅        | Indirect descriptors                    |
 | `VIRTIO_F_EVENT_IDX`         | ❌        | `avail_event` and `used_event` fields   |
 | `VIRTIO_F_VERSION_1`         | TODO      | VirtIO version 1 compliance             |
 | `VIRTIO_F_ACCESS_PLATFORM`   | ❌        | Limited device access to memory         |