Recommend a different AUR helper

Yaourt is long past being recommended. If the user must use an AUR helper yay is much better for many reasons documented on the Arch Wiki.

Author: alexjj

README.md

@@ -122,7 +122,7 @@ There's also a WebUI package available for OpenWrt (`luci-app-https-dns-proxy`)
 
 There is also an externally maintained [AUR package](https://aur.archlinux.org/packages/https-dns-proxy-git/) for latest git version. You can install as follows:
 ```
-user@arch:~# yaourt -S https-dns-proxy-git
+user@arch:~# yay -S https-dns-proxy-git
 ```
 
 ### Docker install