README.adoc: update package information

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2017 - 2022, Přemysl Eric Janouch <p@janouch.name>
+Copyright (c) 2017 - 2023, Přemysl Eric Janouch <p@janouch.name>
 
 Permission to use, copy, modify, and/or distribute this software for any
 purpose with or without fee is hereby granted.

README.adoc

@@ -18,8 +18,10 @@ image::sdn.png[align="center"]
 
 Packages
 --------
-Regular releases are sporadic.  git master should be stable enough.  You can get
+Regular releases are sporadic.  git master should be stable enough.
-a package with the latest development version from Archlinux's AUR.
+You can get a package with the latest development version using Arch Linux's
+https://aur.archlinux.org/packages/sdn-git[AUR],
+or as a https://git.janouch.name/p/nixexprs[Nix derivation].
 
 Building
 --------

sdn.cpp

@@ -1,7 +1,7 @@
 //
 // sdn: simple directory navigator
 //
-// Copyright (c) 2017 - 2022, Přemysl Eric Janouch <p@janouch.name>
+// Copyright (c) 2017 - 2023, Přemysl Eric Janouch <p@janouch.name>
 //
 // Permission to use, copy, modify, and/or distribute this software for any
 // purpose with or without fee is hereby granted.