[gnome-devel-docs] Remove a 404 link to a presentation from 2002

[Andre Klapper <aklapper src gnome org>]

commit 6fc9eacee408317a8e4594534f2cf73a08ace530
Author: Andre Klapper <a9016009 gmx de>
Date:   Sat Apr 25 16:34:38 2020 +0200

    Remove a 404 link to a presentation from 2002

 accessibility-devel-guide/C/gad.xml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/accessibility-devel-guide/C/gad.xml b/accessibility-devel-guide/C/gad.xml
index 094e8fc5..9d084607 100644
--- a/accessibility-devel-guide/C/gad.xml
+++ b/accessibility-devel-guide/C/gad.xml
@@ -169,7 +169,7 @@ If your application only uses standard GTK widgets, you will probably have to do
 You can probably also improve on the default descriptions provided for some of the widgets, and tailor them 
to that widget's specific purpose in your application. You should add or change the textual descriptions for 
these widgets with the appropriate ATK function call, so that an assistive technology can describe their 
purpose or state to the user. See <link linkend="gad-coding-guidelines">Coding Guidelines for Supporting 
Accessibility</link> for more information.
 </para>
 <para>
-If your application uses custom widgets, you may have to do some work to expose those widgets' properties to 
assistive technologies.  See <link linkend="gad-custom">Making Custom Components Accessible</link> and <link 
linkend="gad-api-examples">Examples that Use the Accessibility API</link> for more information. Additional 
detailed information can be found in Marc Mulcahy's 2002 GUADEC presentation, <ulink 
url="https://projects.gnome.org/accessibility/talks/GUAD3C/making-apps-accessible/start.html";>"Making GNOME 
Applications Accessible".</ulink>
+If your application uses custom widgets, you may have to do some work to expose those widgets' properties to 
assistive technologies.  See <link linkend="gad-custom">Making Custom Components Accessible</link> and <link 
linkend="gad-api-examples">Examples that Use the Accessibility API</link> for more information.
 </para>
 </section>