Add version info to API docs.

docs/reference/gobject/Makefile.am

@@ -32,10 +32,10 @@ EXTRA_HFILES=
 HTML_IMAGES =
 
 # Extra SGML files that are included by $(DOC_MAIN_SGML_FILE)
-content_files =
+content_files = version.xml
 
 # Other files to distribute
-extra_files =
+extra_files = version.xml.in
 
 # CFLAGS and LDFLAGS for compiling scan program. Only needed
 # if $(DOC_MODULE).types is non-empty.

docs/reference/gobject/gobject-docs.sgml

@@ -14,10 +14,12 @@
 <!ENTITY gobject-Signals SYSTEM "xml/signals.xml">
 <!ENTITY gobject-Closures SYSTEM "xml/gclosure.xml">
 <!ENTITY gobject-Value-Arrays SYSTEM "xml/value_arrays.xml">
+<!ENTITY version SYSTEM "version.xml">
 ]>
 <book id="index">
   <bookinfo>
     <title>GObject Reference Manual</title>
+    <releaseinfo>for GLib &version;</releaseinfo>
   </bookinfo>
 
   <preface>

docs/reference/gobject/version.xml.in

@@ -0,0 +1 @@
+@GLIB_VERSION@