[gtk+] docs: Fix a duplicate ID

[Matthias Clasen <matthiasc src gnome org>]

commit 3bed458723b7dfb162f9498fc5a50b32eebdf224
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon May 30 20:21:48 2016 -0400

    docs: Fix a duplicate ID
    
    This was causing navigation in the online docs to be confused.

 docs/reference/gtk/migrating-3xtoy.xml |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/docs/reference/gtk/migrating-3xtoy.xml b/docs/reference/gtk/migrating-3xtoy.xml
index ea4ebb4..19fd608 100644
--- a/docs/reference/gtk/migrating-3xtoy.xml
+++ b/docs/reference/gtk/migrating-3xtoy.xml
@@ -3,7 +3,7 @@
                "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd"; [
 <!ENTITY % local.common.attrib "xmlns:xi  CDATA  #FIXED 'http://www.w3.org/2003/XInclude'">
 ]>
-<chapter id="gtk-migrating-2-to-3">
+<chapter id="gtk-migrating-3-x-to-y">
   <title>Migrating from one GTK+ 3 release to another</title>
 
   <para>