docs: add PKGBUILD and installation instructions for Archlinux

Fixes: #215

PKGBUILD

@@ -0,0 +1,19 @@
+pkgname='eask'
+pkgver=$(git tag --sort=-creatordate | head -n1).$(git rev-parse --short HEAD)
+pkgrel=1
+pkgdesc='CLI for building, running, testing, and managing your Emacs Lisp dependencies'
+arch=('x86_64')
+makedepends=('npm')
+url='https://github.com/emacs-eask/cli'
+license=('GPL-3.0')
+
+prepare() {
+    npm i && npm i pkg # `pkg` is not among deps
+    npm run pkg-linux-x64
+}
+
+package() {
+    mkdir -p "$pkgdir/usr/bin"
+    # ATM eask only works when `lisp` dir is installed together with the binary
+    cp -r "${startdir}/lisp" "${startdir}/dist/eask" "$pkgdir/usr/bin"
+}

docs/content/Getting-Started/Install-Eask/_index.en.md

@@ -90,6 +90,15 @@ automatically updated.
 $ sudo snap install eask-cli
 ```
 
+### 📦 Arch (Linux)
+
+There's a `PKGBUILD` that builds `eask` from sources and creates a package, so
+inside the top directory of the repository you can simply run:
+
+```sh
+$ makepkg -i
+```
+
 ### 📦 Chocolatey (Windows)
 
 If you have [Chocolatey](https://chocolatey.org/) installed on your machine, you can
@@ -150,7 +159,7 @@ On Windows,
 set PATH=%PATH%;c:/path/to/eask/bin
 ```
 
-Once you have set it up correctly, try `eask --version` then you should see 
+Once you have set it up correctly, try `eask --version` then you should see
 the current eask's version number! 🎉 🎊