[gtk/issue-2820] docs: Update the link to the GtkBuilder schema

[Emmanuele Bassi <ebassi src gnome org>]

commit e9c4c801029de3287bf425268a4af1e1ba51fdc2
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Fri Jun 5 10:16:19 2020 +0100

    docs: Update the link to the GtkBuilder schema
    
    The link to the file is still using the old cgit format, which redirects
    to master, where the RNC file is gone.
    
    Fixes: #2820

 gtk/gtkbuilder.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/gtkbuilder.c b/gtk/gtkbuilder.c
index 84db789496..d525d952c3 100644
--- a/gtk/gtkbuilder.c
+++ b/gtk/gtkbuilder.c
@@ -67,7 +67,7 @@
  * It is common to use `.ui` as the filename extension for files containing
  * GtkBuilder UI definitions.
  *
- * [RELAX NG Compact Syntax](https://git.gnome.org/browse/gtk+/tree/gtk/gtkbuilder.rnc)
+ * [RELAX NG Compact Syntax](https://gitlab.gnome.org/GNOME/gtk/-/blob/gtk-3-24/gtk/gtkbuilder.rnc)
  *
  * The toplevel element is <interface>. It optionally takes a “domain”
  * attribute, which will make the builder look for translated strings