[gtk] texttag: Replace gtk3-demo reference with gtk4-demo

[Mohammed Sadiq <pksadiq src gnome org>]

commit dcd21e12cdc8006e7ad768c85210fa01392dc92a
Author: Mohammed Sadiq <sadiq sadiqpk org>
Date:   Wed Nov 28 16:51:45 2018 +0530

    texttag: Replace gtk3-demo reference with gtk4-demo

 gtk/gtktexttag.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/gtktexttag.c b/gtk/gtktexttag.c
index f357b3eba8..27fbdff6b7 100644
--- a/gtk/gtktexttag.c
+++ b/gtk/gtktexttag.c
@@ -61,7 +61,7 @@
  * before using them with that buffer.
  *
  * gtk_text_buffer_create_tag() is the best way to create tags.
- * See “gtk3-demo” for numerous examples.
+ * See “gtk4-demo” for numerous examples.
  *
  * For each property of #GtkTextTag, there is a “set” property, e.g.
  * “font-set” corresponds to “font”. These “set” properties reflect