[gtkmm-documentation/gtkmm-3-22] Link to glibmm 2.58

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 08466ba5a5ed32197f589da6ccd0182ae8823016
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Wed Nov 7 10:50:13 2018 +0100

    Link to glibmm 2.58
    
    It's the latest glibmm version in the glibmm-2.4 ABI series.
    This ABI series is compatible with gtkmm3.

 docs/tutorial/C/index-in.docbook | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/docs/tutorial/C/index-in.docbook b/docs/tutorial/C/index-in.docbook
index 6925b81..e424e36 100644
--- a/docs/tutorial/C/index-in.docbook
+++ b/docs/tutorial/C/index-in.docbook
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://docbook.org/docbook/xml/4.5/docbookx.dtd"; [
-  <!ENTITY url_refdocs_base_glib_html "http://developer.gnome.org/glibmm/2.50/";>
+  <!ENTITY url_refdocs_base_glib_html "http://developer.gnome.org/glibmm/2.58/";>
   <!ENTITY url_refdocs_base_glib "&url_refdocs_base_glib_html;classGlib_1_1">
   <!ENTITY url_refdocs_base_gio "&url_refdocs_base_glib_html;classGio_1_1">
   <!ENTITY url_refdocs_base_gtk_html "http://developer.gnome.org/gtkmm/3.22/";>