docs: rename *-docs.sgml to *-docs.xml

We are using xml docbook nowadays

docs/reference/gio/gio-docs.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
-               "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [
+<!DOCTYPE book PUBLIC '-//OASIS//DTD DocBook XML V4.5//EN'
+                      'http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd' [
 <!ENTITY % local.common.attrib "xmlns:xi  CDATA  #FIXED 'http://www.w3.org/2003/XInclude'">
 <!ENTITY version SYSTEM "version.xml">
 ]>

docs/reference/glib/Makefile.am

@@ -7,7 +7,7 @@ AUTOMAKE_OPTIONS = 1.6
 DOC_MODULE=glib
 
 # The top-level SGML file.
-DOC_MAIN_SGML_FILE=glib-docs.sgml
+DOC_MAIN_SGML_FILE=glib-docs.xml
 
 # The directory containing the source code. Relative to $(srcdir)
 DOC_SOURCE_DIR=$(top_srcdir)/glib $(top_srcdir)/gmodule
@@ -60,13 +60,13 @@ HTML_IMAGES =  				\
 
 # Extra SGML files that are included by $(DOC_MAIN_SGML_FILE)
 content_files =				\
-	cross.sgml			\
-	running.sgml			\
-	building.sgml			\
-	changes.sgml			\
-	compiling.sgml			\
-	resources.sgml			\
-	regex-syntax.sgml		\
+	cross.xml			\
+	running.xml			\
+	building.xml			\
+	changes.xml			\
+	compiling.xml			\
+	resources.xml			\
+	regex-syntax.xml		\
 	version.xml			\
 	glib-gettextize.xml		\
 	gtester.xml			\
@@ -75,7 +75,7 @@ content_files =				\
 	gvariant-text.xml
 
 expand_content_files = 			\
-	compiling.sgml
+	compiling.xml
 
 # Extra options to supply to gtkdoc-fixref
 FIXXREF_OPTIONS=--extra-dir=$(srcdir)/../gobject/html --extra-dir=$(srcdir)/../gio/html

docs/reference/glib/glib-docs.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
-               "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [
+<!DOCTYPE book PUBLIC '-//OASIS//DTD DocBook XML V4.5//EN'
+                      'http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd' [
 <!ENTITY % local.common.attrib "xmlns:xi  CDATA  #FIXED 'http://www.w3.org/2003/XInclude'">
 <!ENTITY version SYSTEM "version.xml">
 ]>
@@ -30,12 +30,12 @@
       structure, they must use a lock to synchronize their operation.
     </para>
 
-    <xi:include href="building.sgml" />
-    <xi:include href="cross.sgml" />
-    <xi:include href="xml/compiling.sgml" />
-    <xi:include href="running.sgml" />
-    <xi:include href="changes.sgml" />
-    <xi:include href="resources.sgml" />
+    <xi:include href="building.xml" />
+    <xi:include href="cross.xml" />
+    <xi:include href="xml/compiling.xml" />
+    <xi:include href="running.xml" />
+    <xi:include href="changes.xml" />
+    <xi:include href="resources.xml" />
 
   </chapter>
 
@@ -91,7 +91,7 @@
     <xi:include href="xml/option.xml" />
     <xi:include href="xml/patterns.xml" />
     <xi:include href="xml/gregex.xml" />
-    <xi:include href="regex-syntax.sgml" />
+    <xi:include href="regex-syntax.xml" />
     <xi:include href="xml/markup.xml" />
     <xi:include href="xml/keyfile.xml" />
     <xi:include href="xml/bookmarkfile.xml" />

docs/reference/gobject/Makefile.am

@@ -7,7 +7,7 @@ AUTOMAKE_OPTIONS = 1.6
 DOC_MODULE=gobject
 
 # The top-level SGML file.
-DOC_MAIN_SGML_FILE=gobject-docs.sgml
+DOC_MAIN_SGML_FILE=gobject-docs.xml
 
 # The directory containing the source code. Relative to $(srcdir)
 DOC_SOURCE_DIR=$(top_srcdir)/gobject

docs/reference/gobject/gobject-docs.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" 
-               "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [
+<!DOCTYPE book PUBLIC '-//OASIS//DTD DocBook XML V4.5//EN'
+                      'http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd' [
 
 <!ENTITY % local.common.attrib "xmlns:xi  CDATA  #FIXED 'http://www.w3.org/2003/XInclude'">
 <!ENTITY version SYSTEM "version.xml">