docs(api): add nuxi prepare command

docs/content/3.api/5.commands/prepare.md

@@ -0,0 +1,11 @@
+# `nuxi prepare`
+
+```{bash}
+npx nuxi prepare [rootDir]
+```
+
+The `prepare` command creates a `.nuxt` directory in your application and generates types. This can be useful in a CI environment or as a `postinstall` command in your `package.json`.
+
+Option        | Default          | Description
+-------------------------|-----------------|------------------
+`rootDir` | `.` | The root directory of the application to prepare.