docs: Use entity for version

Meson's gtk-doc support currently requires the main SGML/XML file
to be located in the srcdir, so instead of substituting the module
version in that file directly, use a small auxiliary file that's
included via a custom entity.

https://bugzilla.gnome.org/show_bug.cgi?id=783229

configure.ac

@@ -254,9 +254,9 @@ AC_CONFIG_FILES([
   docs/Makefile
   docs/reference/Makefile
   docs/reference/shell/Makefile
-  docs/reference/shell/shell-docs.sgml
+  docs/reference/shell/version.xml
   docs/reference/st/Makefile
-  docs/reference/st/st-docs.sgml
+  docs/reference/st/version.xml
   js/Makefile
   src/Makefile
   subprojects/gvc/Makefile

docs/reference/shell/Makefile.am

@@ -120,7 +120,7 @@ include $(top_srcdir)/gtk-doc.make
 
 # Other files to distribute
 # e.g. EXTRA_DIST += version.xml.in
-EXTRA_DIST +=
+EXTRA_DIST += version.xml.in
 
 # Files not to distribute
 # for --rebuild-types in $(SCAN_OPTIONS), e.g. $(DOC_MODULE).types

docs/reference/shell/shell-docs.sgml

@@ -3,12 +3,13 @@
                "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'">
+  <!ENTITY version SYSTEM "version.xml">
 ]>
 <book id="index">
   <bookinfo>
     <title>Shell Reference Manual</title>
     <releaseinfo>
-      for Shell @VERSION@.
+      for Shell &version;.
       <!--The latest version of this documentation can be found on-line at
       <ulink role="online-location" url="http://[SERVER]/shell/index.html">http://[SERVER]/shell/</ulink>.-->
     </releaseinfo>

docs/reference/shell/version.xml.in

@@ -0,0 +1 @@
+@VERSION@

docs/reference/st/Makefile.am

@@ -85,7 +85,7 @@ include $(top_srcdir)/gtk-doc.make
 
 # Other files to distribute
 # e.g. EXTRA_DIST += version.xml.in
-EXTRA_DIST +=
+EXTRA_DIST += version.xml.in
 
 # Files not to distribute
 # for --rebuild-types in $(SCAN_OPTIONS), e.g. $(DOC_MODULE).types

docs/reference/st/st-docs.sgml

@@ -3,12 +3,13 @@
                "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'">
+  <!ENTITY version SYSTEM "version.xml">
 ]>
 <book id="index">
   <bookinfo>
     <title>St Reference Manual</title>
     <releaseinfo>
-      for St @VERSION@.
+      for St &version;.
       <!--The latest version of this documentation can be found on-line at
       <ulink role="online-location" url="http://[SERVER]/st/index.html">http://[SERVER]/st/</ulink>.-->
     </releaseinfo>

docs/reference/st/version.xml.in

@@ -0,0 +1 @@
+@VERSION@