[devhelp] help: update a URL

[Sébastien Wilmet <swilmet src gnome org>]

commit 582ab70c50bdbf02c0433ddb4ddc795fb8efc06a
Author: Sébastien Wilmet <sw swilmet be>
Date:   Sun Jan 10 16:34:03 2021 +0100

    help: update a URL
    
    Fixes https://gitlab.gnome.org/GNOME/devhelp/-/issues/26

 help/C/installing-api-documentation.page | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/help/C/installing-api-documentation.page b/help/C/installing-api-documentation.page
index 837226cf..c3b5ba8c 100644
--- a/help/C/installing-api-documentation.page
+++ b/help/C/installing-api-documentation.page
@@ -78,9 +78,9 @@ SPDX-License-Identifier: CC-BY-SA-4.0
 <section id="gtk-doc">
   <title>GTK-Doc</title>
   <p>
-    <link href="https://www.gtk.org/gtk-doc/";>GTK-Doc</link> is a tool to
-    generate API documentation from comments added to C code. It is used by
-    GLib, GTK and GNOME libraries and applications.
+    <link href="https://gitlab.gnome.org/GNOME/gtk-doc";>GTK-Doc</link> is a
+    tool to generate API documentation from comments added to C code. It is
+    used by GLib, GTK and GNOME libraries and applications.
   </p>
   <p>
     GTK-Doc installs the API reference of a module into: