[libhandy] Update Deck and Leaflet insert functions docs following GTK4 docs

[Alexander Mikhaylenko <alexm src gnome org>]

commit 9edf31a32753c4a1967c39f1d8e5b682ad8e6b37
Author: Yetizone <andreii lisita gmail com>
Date:   Mon Dec 21 18:05:11 2020 +0200

    Update Deck and Leaflet insert functions docs following GTK4 docs
    
    See https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/2981

 src/hdy-deck.c    | 2 +-
 src/hdy-leaflet.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/hdy-deck.c b/src/hdy-deck.c
index 0736cfb0..fe0e3a80 100644
--- a/src/hdy-deck.c
+++ b/src/hdy-deck.c
@@ -555,7 +555,7 @@ hdy_deck_prepend (HdyDeck   *self,
  * hdy_deck_insert_child_after:
  * @self: a #HdyDeck
  * @child: the #GtkWidget to insert
- * @sibling: (nullable): the sibling to insert @child after, or %NULL
+ * @sibling: (nullable): the sibling after which to insert @child
  *
  * Inserts @child in the position after @sibling in the list of children.
  * If @sibling is %NULL, insert @child at the first position.
diff --git a/src/hdy-leaflet.c b/src/hdy-leaflet.c
index 01d2fa34..0f3b7b1a 100644
--- a/src/hdy-leaflet.c
+++ b/src/hdy-leaflet.c
@@ -599,7 +599,7 @@ hdy_leaflet_prepend (HdyLeaflet *self,
  * hdy_leaflet_insert_child_after:
  * @self: a #HdyLeaflet
  * @child: the #GtkWidget to insert
- * @sibling: (nullable): the sibling to insert @child after, or %NULL
+ * @sibling: (nullable): the sibling after which to insert @child
  *
  * Inserts @child in the position after @sibling in the list of children.
  * If @sibling is %NULL, insert @child at the first position.