Add a Recipe Examples section to the docs

We should add a new section to the docs that creates recipe.yml snippets on how to do common tasks.

* How to add a field to every content type

https://github.com/kanopi/saplings-fields-seo/blob/main/recipe.yml

* Ask for a role's machine name and add permissions to it.

user.role.${role_name}:
  createIfNotExists: ...
  grantPermission: ...