Add a list of page layouts

I've made a lot of changes to the site recently, and some small inconsistencies are creeping in to the page templates. Some very similar pages use different templates. And some layout stuff is stored in individual pages, making it more difficult to manage.

By adding a list of different page types I can start to make them more consistent.

User story

As a user, I need the website pages to be consistent, so that I can read and browse them easily.

Acceptance criteria

• Add a list of different page types to the style guide
• Include a link to an example for each