[ghex] hex-buffer-iface: docs: Add reference to _write_to_file_async

[Logan Rathbone <larathbone src gnome org>]

commit ae48da036d1b758325b1ad00d12a4ddaf27608b4
Author: Logan Rathbone <poprocks gmail com>
Date:   Tue Jun 7 12:11:58 2022 -0400

    hex-buffer-iface: docs: Add reference to _write_to_file_async
    
    Remove FIXME comment as a result.

 src/hex-buffer-iface.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/hex-buffer-iface.c b/src/hex-buffer-iface.c
index 89ad960..9093f7b 100644
--- a/src/hex-buffer-iface.c
+++ b/src/hex-buffer-iface.c
@@ -241,11 +241,11 @@ hex_buffer_read_finish (HexBuffer *self,
  * hex_buffer_write_to_file:
  * @file: #GFile to write to
  *
- * Write the buffer to the #GFile specified. This operation will block.
+ * Write the buffer to the #GFile specified. This operation will block. For a
+ * non-blocking version, use [method@Hex.Buffer.write_to_file_async].
  *
  * Returns: %TRUE if the operation was successful; %FALSE otherwise.
  */
-/* FIXME - insert reference to async version if/when it is written. */
 gboolean
 hex_buffer_write_to_file (HexBuffer *self, GFile *file)
 {