[gdk-pixbuf] docs: Add missing index for 2.40 symbols

[Emmanuele Bassi <ebassi src gnome org>]

commit dae878bb2362abe4b8705930825d3ec617dcbc62
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Mon Nov 9 12:06:38 2020 +0000

    docs: Add missing index for 2.40 symbols

 docs/gdk-pixbuf.xml | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/docs/gdk-pixbuf.xml b/docs/gdk-pixbuf.xml
index f1e0db0182..efe977bdd0 100644
--- a/docs/gdk-pixbuf.xml
+++ b/docs/gdk-pixbuf.xml
@@ -182,6 +182,10 @@
     <title>Index of new symbols in 2.38</title>
     <xi:include href="xml/api-index-2.38.xml"><xi:fallback /></xi:include>
   </index>
+  <index id="api-index-2-40" role="2.40">
+    <title>Index of new symbols in 2.40</title>
+    <xi:include href="xml/api-index-2.40.xml"><xi:fallback /></xi:include>
+  </index>
 
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