Update stable version to 19.03

Also prepares for 19.09.

README.md

@@ -19,7 +19,7 @@ will write to your dconf store and cannot tell whether a configuration
 that it is about to be overwrite was from a previous Home Manager
 generation or from manual configuration.
 
-Home Manager targets [NixOS][] unstable and NixOS version 18.09 (the
+Home Manager targets [NixOS][] unstable and NixOS version 19.03 (the
 current stable version), it may or may not work on other Linux
 distributions and NixOS versions.
 
@@ -72,11 +72,11 @@ Currently the easiest way to install Home Manager is as follows:
     if you are following Nixpkgs master or an unstable channel and
 
     ```console
-    $ nix-channel --add https://github.com/rycee/home-manager/archive/release-18.09.tar.gz home-manager
+    $ nix-channel --add https://github.com/rycee/home-manager/archive/release-19.03.tar.gz home-manager
     $ nix-channel --update
     ```
 
-    if you follow a Nixpkgs version 18.09 channel.
+    if you follow a Nixpkgs version 19.03 channel.
 
     On NixOS you may need to log out and back in for the channel to
     become available. On non-NixOS you may have to add

doc/installation.xml

@@ -79,11 +79,11 @@
      if you are following Nixpkgs master or an unstable channel and
     </para>
 <screen>
-<prompt>$</prompt> <userinput>nix-channel --add https://github.com/rycee/home-manager/archive/release-18.09.tar.gz home-manager</userinput>
+<prompt>$</prompt> <userinput>nix-channel --add https://github.com/rycee/home-manager/archive/release-19.03.tar.gz home-manager</userinput>
 <prompt>$</prompt> <userinput>nix-channel --update</userinput>
 </screen>
     <para>
-     if you follow a Nixpkgs version 18.09 channel.
+     if you follow a Nixpkgs version 19.03 channel.
     </para>
     <para>
      On NixOS you may need to log out and back in for the channel to become
@@ -169,12 +169,12 @@ $HOME/.nix-profile/etc/profile.d/hm-session-vars.sh
   </para>
 
 <screen>
-<prompt>#</prompt> <userinput>nix-channel --add https://github.com/rycee/home-manager/archive/release-18.09.tar.gz home-manager</userinput>
+<prompt>#</prompt> <userinput>nix-channel --add https://github.com/rycee/home-manager/archive/release-19.03.tar.gz home-manager</userinput>
 <prompt>#</prompt> <userinput>nix-channel --update</userinput>
 </screen>
 
   <para>
-   if you follow a Nixpkgs version 18.09 channel.
+   if you follow a Nixpkgs version 19.03 channel.
   </para>
 
   <para>

doc/release-notes/release-notes.xml

@@ -8,6 +8,7 @@
   This section lists the release notes for stable versions of Home Manager and
   the current unstable version.
  </para>
+ <xi:include href="rl-1909.xml" />
  <xi:include href="rl-1903.xml" />
  <xi:include href="rl-1809.xml" />
 </appendix>

doc/release-notes/rl-1903.xml

@@ -3,15 +3,10 @@
          xmlns:xi="http://www.w3.org/2001/XInclude"
          version="5.0"
          xml:id="sec-release-19.03">
- <title>Release 19.03 (unstable)</title>
+ <title>Release 19.03</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.
+  The 19.03 release branch became the stable branch in April, 2019.
  </para>
 
  <section xmlns="http://docbook.org/ns/docbook"

doc/release-notes/rl-1909.xml

@@ -0,0 +1,12 @@
+<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-19.09">
+ <title>Release 19.09 (unreleased)</title>
+
+ <para>
+  This is the current unstable branch and the information in this section is
+  therefore not final.
+ </para>
+</section>

modules/misc/version.nix

@@ -5,7 +5,7 @@ with lib;
 {
   options = {
     home.stateVersion = mkOption {
-      type = types.enum [ "18.09" "19.03" ];
+      type = types.enum [ "18.09" "19.03" "19.09" ];
       default = "18.09";
       description = ''
         It is occasionally necessary for Home Manager to change