doc: add basic release notes

(cherry picked from commit c035046999)

doc/default.nix

@@ -119,6 +119,7 @@ let
       <toc role="chunk-toc">
         <d:tocentry xmlns:d="http://docbook.org/ns/docbook" linkend="book-home-manager-manual"><?dbhtml filename="index.html"?>
           <d:tocentry linkend="ch-options"><?dbhtml filename="options.html"?></d:tocentry>
+          <d:tocentry linkend="ch-release-notes"><?dbhtml filename="release-notes.html"?></d:tocentry>
         </d:tocentry>
       </toc>
     '';

doc/manual.xml

@@ -29,4 +29,5 @@
   <title>Configuration Options</title>
   <xi:include href="./generated/options-db.xml" xpointer="configuration-variable-list" />
  </appendix>
+ <xi:include href="./release-notes/release-notes.xml" />
 </book>

doc/release-notes/release-notes.xml

@@ -0,0 +1,13 @@
+<appendix xmlns="http://docbook.org/ns/docbook"
+          xmlns:xlink="http://www.w3.org/1999/xlink"
+          xmlns:xi="http://www.w3.org/2001/XInclude"
+          version="5.0"
+          xml:id="ch-release-notes">
+ <title>Release Notes</title>
+ <para>
+  This section lists the release notes for stable versions of Home Manager and
+  the current unstable version.
+ </para>
+ <xi:include href="rl-1903.xml" />
+ <xi:include href="rl-1809.xml" />
+</appendix>

doc/release-notes/rl-1809.xml

@@ -0,0 +1,11 @@
+<section xmlns="http://docbook.org/ns/docbook"
+         xmlns:xlink="http://www.w3.org/1999/xlink"
+         xmlns:xi="http://www.w3.org/2001/XInclude"
+         version="5.0"
+         xml:id="sec-release-18.09">
+ <title>Release 18.09</title>
+
+ <para>
+  The 18.09 release branch became the stable branch in September, 2018.
+ </para>
+</section>

doc/release-notes/rl-1903.xml

@@ -0,0 +1,67 @@
+<section xmlns="http://docbook.org/ns/docbook"
+         xmlns:xlink="http://www.w3.org/1999/xlink"
+         xmlns:xi="http://www.w3.org/2001/XInclude"
+         version="5.0"
+         xml:id="sec-release-19.03">
+ <title>Release 19.03 (unstable)</title>
+
+ <para>
+  This is the current unstable branch and the information in this section is
+  therefore not final.
+ </para>
+
+ <para>
+  Scheduled released is March, 2019.
+ </para>
+
+ <section xmlns="http://docbook.org/ns/docbook"
+         xmlns:xlink="http://www.w3.org/1999/xlink"
+         xmlns:xi="http://www.w3.org/2001/XInclude"
+         version="5.0"
+         xml:id="sec-release-19.03-highlights">
+  <title>Highlights</title>
+
+  <para>
+   This release has the following notable changes:
+  </para>
+
+  <itemizedlist>
+   <listitem>
+    <para>
+     The <option>home.file.&lt;name?&gt;.source</option> now allows source
+     files to be hidden, that is, having a name starting with the
+     <literal>.</literal> character. It also allows the source file name to
+     contain characters not typically allowed for Nix store paths. For example,
+     your configuration can now contain things such as
+<programlisting>
+home.file."my file".source = ./. + "/file with spaces!";
+</programlisting>
+    </para>
+   </listitem>
+  </itemizedlist>
+ </section>
+
+ <section xmlns="http://docbook.org/ns/docbook"
+         xmlns:xlink="http://www.w3.org/1999/xlink"
+         xmlns:xi="http://www.w3.org/2001/XInclude"
+         version="5.0"
+         xml:id="sec-release-19.03-state-version-changes">
+  <title>State Version Changes</title>
+
+  <para>
+   The state version in this release includes the changes below. These changes
+   are only active if the <option>home.stateVersion</option> option is set to
+   "19.03" or later.
+  </para>
+
+  <itemizedlist>
+   <listitem>
+    <para>
+     There is now an option <option>programs.beets.enable</option> that
+     defaults to <literal>false</literal>. Before the module would be active if
+     the <option>programs.beets.settings</option> option was non-empty.
+    </para>
+   </listitem>
+  </itemizedlist>
+ </section>
+</section>