[gdk-pixbuf] docs: Re-organise the API reference index

[Emmanuele Bassi <ebassi src gnome org>]

commit f22ece88215041f38624ac5287ecbc716aef655d
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Sat Sep 1 11:23:51 2018 +0100

    docs: Re-organise the API reference index
    
    Group the sections that are deprecated or that defer to another library,
    to ensure that readers are aware of their status at a glance.

 docs/gdk-pixbuf.xml | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)
---
diff --git a/docs/gdk-pixbuf.xml b/docs/gdk-pixbuf.xml
index f70b57662..2c10c1768 100644
--- a/docs/gdk-pixbuf.xml
+++ b/docs/gdk-pixbuf.xml
@@ -81,18 +81,28 @@
     <xi:include href="xml/creating.xml" />
     <xi:include href="xml/inline.xml" />
     <xi:include href="xml/scaling.xml" />
-    <xi:include href="gdk-pixbuf-rendering.xml" />
-    <xi:include href="gdk-pixbuf-from-drawables.xml" />
     <xi:include href="xml/util.xml" />
     <xi:include href="xml/animation.xml" />
 
-    <xi:include href="xml/gdk-pixbuf-loader.xml" />
-    <xi:include href="xml/module_interface.xml" />
-
-    <xi:include href="xml/gdk-pixbuf-xlib-init.xml" />
-    <xi:include href="xml/gdk-pixbuf-xlib-rendering.xml" />
-    <xi:include href="xml/gdk-pixbuf-xlib-from-drawables.xml" />
-    <xi:include href="xml/gdk-pixbuf-xlib-rgb.xml" />
+    <chapter id="LoadableModules">
+      <title>Loadable modules</title>
+      <xi:include href="xml/module_interface.xml" />
+      <xi:include href="xml/gdk-pixbuf-loader.xml" />
+    </chapter>
+
+    <chapter id="Xlib">
+      <title>Xlib integration (deprecated)</title>
+      <xi:include href="xml/gdk-pixbuf-xlib-init.xml" />
+      <xi:include href="xml/gdk-pixbuf-xlib-rendering.xml" />
+      <xi:include href="xml/gdk-pixbuf-xlib-from-drawables.xml" />
+      <xi:include href="xml/gdk-pixbuf-xlib-rgb.xml" />
+    </chapter>
+
+    <chapter id="Gdk">
+      <title>GDK integration (deprecated)</title>
+      <xi:include href="xml/gdk-pixbuf-rendering.xml" />
+      <xi:include href="xml/gdk-pixbuf-from-drawables.xml" />
+    </chapter>
   </reference>
 
   <reference>