[gtksourceview] NEWS: add note about Vala bindings

[Christian Hergert <chergert src gnome org>]

commit d1247b6c338e32623408c17e7547e3c74820c457
Author: Christian Hergert <chergert redhat com>
Date:   Mon Nov 29 11:24:50 2021 -0800

    NEWS: add note about Vala bindings

 NEWS | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/NEWS b/NEWS
index 447273d5..5ed9517a 100644
--- a/NEWS
+++ b/NEWS
@@ -1,4 +1,8 @@
 
+ * The Vala bindings have moved from the Gtk namespace to the GtkSource
+   namespace to match the bindings in all other languages. While it is
+   unfortunate that this has happened after 5.0, it is still early enough
+   that we can avoid having to maintain a clashing namespace with Gtk.
  * A new Vim emulator in the form of GtkSourceVimIMContext. This can emulate
    basic features such as Normal, Insert, Replace, Visual, Visual Line, and
    Command Bar modes. Additionally, many Vim-style motions and text-objects