doc: Add entities file and use it in index.xml.

This makes re-use of URL fragments or repeated links a lot easier.

Unfortunately we need to declare the XML namespace for every entity that
uses <link/> and xlink which is a bit ugly. :-/

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

2 files changed, 32 insertions, 7 deletions

diff --git a/doc/entities.ent b/doc/entities.ent
new file mode 100644
index 00000000..cee77e2d
--- /dev/null
+++ b/doc/entities.ent
@@ -0,0 +1,22 @@
+<!ENTITY nixos.url "https://nixos.org/">
+<!ENTITY nixpkgs.url "https://nixos.org/nixpkgs/">
+<!ENTITY openlab.url "https://openlab-augsburg.de/">
+
+<!ENTITY nixos '
+<link xmlns="http://docbook.org/ns/docbook"
+      xmlns:xlink="http://www.w3.org/1999/xlink"
+      xlink:href="&nixos.url;">NixOS</link>
+'>
+<!ENTITY nixpkgs '
+<link xmlns="http://docbook.org/ns/docbook"
+      xmlns:xlink="http://www.w3.org/1999/xlink"
+      xlink:href="&nixpkgs.url;">&lt;nixpkgs&gt;</link>
+'>
+<!ENTITY openlab '
+<link xmlns="http://docbook.org/ns/docbook"
+      xmlns:xlink="http://www.w3.org/1999/xlink"
+      xlink:href="&openlab.url;">OpenLab Augsburg</link>
+'>
+
+<!ENTITY hydra.base "https://headcounter.org/hydra">
+<!ENTITY hydra.channelbase "&hydra.base;/channel/custom/openlab/vuizvui">
diff --git a/doc/index.xml b/doc/index.xml
index dd26df3b..5bc76216 100644
--- a/doc/index.xml
+++ b/doc/index.xml
@@ -1,3 +1,8 @@
+<?xml version="1.0"?>
+<!DOCTYPE book [
+<!ENTITY % entities SYSTEM "entities.ent">
+%entities;
+]>
 <book xmlns="http://docbook.org/ns/docbook"
       xmlns:xlink="http://www.w3.org/1999/xlink"
       xmlns:xi="http://www.w3.org/2001/XInclude">
@@ -6,12 +11,10 @@
     <title>What is Vuizvui?</title>
     <para>
       Vuizvui is a set of NixOS modules and machine configurations that aim to
-      extend <ulink url="https://nixos.org/">NixOS</ulink> in a way that fits
-      the needs of the members of the
-      <ulink url="https://openlab-augsburg.de/">OpenLab Augsburg</ulink>
-      and also serves as a playground for experimental features that are yet to
-      be included in the official NixOS project once they're well tested and
-      matured enough.
+      extend &nixos; in a way that fits the needs of the members of the
+      &openlab; and also serves as a playground for experimental features that
+      are yet to be included in the official NixOS project once they're well
+      tested and matured enough.
     </para>
 
     <para>
@@ -25,7 +28,7 @@
       something like <literal>too much</literal> while on the other side
       <literal>nix</literal> means nothing. Which fits quite well because this
       repository is for everything either too complex or not polished/generic
-      enough to be pushed into nixpkgs.
+      enough to be pushed into &nixpkgs;.
     </para>
   </preface>