render/allocator/gbm: fix create() docs for FD ownership

Fixes: d9d8fc1ab9 ("render/allocator: re-open GBM FD")

include/render/allocator/gbm.h

@@ -27,7 +27,7 @@ struct wlr_gbm_allocator {
 /**
  * Creates a new GBM allocator from a DRM FD.
  *
- * Does not take ownership over the FD.
+ * Takes ownership over the FD.
  */
 struct wlr_allocator *wlr_gbm_allocator_create(int drm_fd);