docs: add .nuxtignore docs (#3440)

* docs: add `.nuxtignore` docs

* docs: fix link syntax

* style: lint

* style: add lang

* Update 17.nuxtignore.md

Co-authored-by: Sébastien Chopin <seb@nuxtjs.com>

docs/content/3.docs/2.directory-structure/17.nuxtignore.md

@@ -0,0 +1,31 @@
+---
+icon: IconFile
+title: .nuxtignore
+head.title: .nuxtignore file
+---
+
+# Nuxt ignore file
+
+You can use a `.nuxtignore` file to let Nuxt ignore `layout`, `pages`, `components`, `composables` and `middleware` files in your project’s root directory (`rootDir`) during the build phase. The `.nuxtignore` file is subject to the same specification as `.gitignore` and `.eslintignore` files, in which each line is a glob pattern indicating which files should be ignored.a
+
+**Note**: You can also configure [`ignoreOptions`](/docs/directory-structure/nuxt.config#ignoreoptions), [`ignorePrefix`](/docs/directory-structure/nuxt.config#ignoreprefix) and [`ignore`](/docs/directory-structure/nuxt.config#ignore) in your `nuxt.config` file.
+
+## Example
+
+```bash [.nuxtignore]
+# ignore layout foo.vue
+layouts/foo.vue
+# ignore layout files whose name ends with -ignore.vue
+layouts/*-ignore.vue
+
+# ignore page bar.vue
+pages/bar.vue
+# ignore page inside ignore folder
+pages/ignore/*.vue
+
+# ignore route middleware files under foo folder except foo/bar.js
+middleware/foo/*.js
+!middleware/foo/bar.js
+```
+
+> More details about the spec are in [gitignore doc](https://git-scm.com/docs/gitignore)