docs(readme): add AUR package name to features

Author: qdm12

README.md

@@ -44,7 +44,8 @@ This readme and the [docs/](docs/) directory are **versioned** to match the prog
 ## Features
 
 - Available as a Docker image [`qmcgaw/ddns-updater`](https://hub.docker.com/r/qmcgaw/ddns-updater) and [`ghcr.io/qdm12/ddns-updater`]((https://github.com/qdm12/ddns-updater/pkgs/container/ddns-updater))
-- 🆕 Available as [zero-dependency binaries for Linux, Windows and MacOS](https://github.com/qdm12/ddns-updater/releases)
+- Available as [zero-dependency binaries for Linux, Windows and MacOS](https://github.com/qdm12/ddns-updater/releases)
+- 🆕 Available in the AUR as [`ddns-updater`](https://aur.archlinux.org/packages/ddns-updater) - see #808
 - Updates periodically A records for different DNS providers:
   - Aliyun
   - AllInkl