docs: add self hosting Vue as an option in the installation guide (#923)

Author: skirtles-code

src/guide/installation.md

@@ -2,11 +2,12 @@
 
 Vue.js is built by design to be incrementally adoptable. This means that it can be integrated into a project multiple ways depending on the requirements.
 
-There are three primary ways of adding Vue.js to a project:
+There are four primary ways of adding Vue.js to a project:
 
 1. Import it as a [CDN package](#cdn) on the page
-2. Install it using [npm](#npm)
-3. Use the official [CLI](#cli) to scaffold a project, which provides batteries-included build setups for a modern frontend workflow (e.g., hot-reload, lint-on-save, and much more)
+2. Download the JavaScript files and [host them yourself](#download-and-self-host)
+3. Install it using [npm](#npm)
+4. Use the official [CLI](#cli) to scaffold a project, which provides batteries-included build setups for a modern frontend workflow (e.g., hot-reload, lint-on-save, and much more)
 
 ## リリースノート
 
@@ -36,6 +37,12 @@ Vue を使用する場合は、ブラウザに [Vue Devtools](https://github.com
 
 本番環境では、新しいバージョンによる意図しない不具合を避けるため、特定のバージョン番号とビルド番号にリンクすることをお勧めします。
 
+## Download and Self Host
+
+If you want to avoid using build tools but can't use a CDN in production then you can download the relevant `.js` file and host it using your own web server. You can then include it using a `<script>` tag, just like with the CDN approach.
+
+The files can be browsed and downloaded from a CDN such as [unpkg](https://unpkg.com/browse/vue@next/dist/) or [jsDelivr](https://cdn.jsdelivr.net/npm/vue@next/dist/). The various different files are [explained later](#explanation-of-different-builds) but you would typically want to download both a development build and a production build.
+
 ## npm
 
 Vue による大規模アプリケーションを構築するときには、npm を利用したインストールを推奨します。[Webpack](https://webpack.js.org/) または [Rollup](https://rollupjs.org/) のようなモジュールバンドラーとうまく組み合わせることができます。Vue は[単一ファイルコンポーネント](../guide/single-file-component.html)を作成するための、付随するツールも提供しています。