docs: Use main branch instead of master

The old name still works but let's use the current name.

diff --git a/docs/reference/gtk/resources.sgml b/docs/reference/gtk/resources.sgml
index e51e3825bb43f2de5aedccd6d2ab96684a4869ce..eeca69a0eec6df242b37c9f2997fc33fd571e54f 100644 (file)
--- a/docs/reference/gtk/resources.sgml
+++ b/docs/reference/gtk/resources.sgml
@@ -51,7 +51,7 @@ questions will be directed to Discourse.
 
 <para>
 Please, follow the instructions outlined in the
-<ulink url="https://gitlab.gnome.org/GNOME/gtk/-/blob/master/CONTRIBUTING.md">Contribution Guide</ulink> available in the GTK
+<ulink url="https://gitlab.gnome.org/GNOME/gtk/-/blob/main/CONTRIBUTING.md">Contribution Guide</ulink> available in the GTK
 source code repository.
 </para>