19.09 is Loris.

https://en.wikipedia.org/wiki/Loris

.version

@@ -1 +1 @@
-19.03
+19.09

lib/trivial.nix

@@ -134,7 +134,7 @@ rec {
      On each release the first letter is bumped and a new animal is chosen
      starting with that new letter.
   */
-  codeName = "Koi";
+  codeName = "Loris";
 
   /* Returns the current nixpkgs version suffix as string. */
   versionSuffix =

nixos/doc/manual/release-notes/release-notes.xml

@@ -8,6 +8,7 @@
   This section lists the release notes for each stable version of NixOS and
   current unstable revision.
  </para>
+ <xi:include href="rl-1909.xml" />
  <xi:include href="rl-1903.xml" />
  <xi:include href="rl-1809.xml" />
  <xi:include href="rl-1803.xml" />

nixos/doc/manual/release-notes/rl-1909.xml

@@ -0,0 +1,58 @@
+<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 (“Loris”, 2019/09/??)</title>
+
+ <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-highlights">
+  <title>Highlights</title>
+
+  <para>
+   In addition to numerous new and upgraded packages, this release has the
+   following highlights:
+  </para>
+
+  <itemizedlist>
+   <listitem>
+    <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-19.09-new-services">
+  <title>New Services</title>
+
+  <para>
+   The following new services were added since the last release:
+  </para>
+
+  <itemizedlist>
+   <listitem>
+    <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-19.09-notable-changes">
+  <title>Other Notable Changes</title>
+
+  <itemizedlist>
+   <listitem>
+    <para />
+   </listitem>
+  </itemizedlist>
+ </section>
+</section>