Added: solidjs/meta install hint (#969)

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>
Co-authored-by: Sarah <gerrardsarah@gmail.com>

Author: 3 people

src/routes/solid-start/building-your-application/head-and-metadata.mdx

@@ -5,6 +5,12 @@ title: "Head and metadata"
 SolidStart does not come with a metadata library.
 In cases where you want to customize the content in the `head` of your `document`, you can use the `@solidjs/meta` library.
 
+<div id="npm">
+```bash frame="none"
+npm i @solidjs/meta
+```
+</div>
+
 The common elements used in the [`head`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/head) are:
 
 - [`title`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/title): Specifies the title of the page, used by the browser tab and headings of search results.