Add Arch Linux (AUR) installation instructions

docs/INSTALL.md

@@ -7,6 +7,7 @@ but compiling on Windows and macOS should be possible with the right tools.
   - [Linux](#linux)
     - [Flatpak](#flatpak)
     - [Alpine Linux / postmarketOS](#alpine-linux--postmarketOS)
+    - [Arch Linux](#arch-linux)
 - [Manual installation](#manual-installation)
   - [Environment variables](#environment-variables)
   - [Package manager dependencies](#package-manager-dependencies)
@@ -95,6 +96,20 @@ apk add moment
 If you are unsure about what Edge is and want to read more about it, you can do
 so on the [Alpine Wiki](https://wiki.alpinelinux.org/wiki/Edge).
 
+#### Arch Linux
+
+AUR packages for the
+[latest stable release](https://aur.archlinux.org/packages/moment/) and
+[git `dev` branch](https://aur.archlinux.org/packages/moment-git/) are
+available.
+
+Installing the release version with an AUR helper, e.g.
+[yay](https://github.com/Jguer/yay):
+
+```sh
+yay -S moment
+```
+
 ## Manual Installation
 
 **Qt 5.12+**, **Python 3.6+** (with **pip** to install packages from the