Add install command for Alpine Linux

README.md

@@ -152,6 +152,7 @@ Intrigued? Find out [HOW](https://github.com/jarun/nnn/wiki/performance-factors)
 
 #### From a package manager
 
+- [Alpine Linux](https://pkgs.alpinelinux.org/packages?name=nnn) (`apk add nnn`)
 - [Arch Linux](https://www.archlinux.org/packages/community/x86_64/nnn/) (`pacman -S nnn`)
 - [Debian](https://packages.debian.org/search?keywords=nnn&searchon=names&exact=1) (`apt-get install nnn`)
 - [Fedora](https://apps.fedoraproject.org/packages/nnn) (`dnf install nnn`)