Add "Guides" category to CMS

[mradamcox]

We already have two categories of content in the CMS, Posts and Showcases, now we need a third, Guides. These are research guides on a specific SDOH topic. This will begin with a new entry in the collections section of the config YAML: https://github.com/healthyregions/SDOHPlace/blob/main/public/admin/config.yml.

The new collection will need these properties at least:

-  name: "guide" # Used in routes, e.g., /admin/collections/blog
    label: "Guide" # Used in the UI
    folder: "content/guides" # The path to the folder where the MDX files are stored
    extension: "mdx"
    format: "frontmatter"
    create: true # Allow users to create new documents in this collection
    slug: "{{slug}}"

The fields section can mimic the "showcase" collection generally (there are good examples of all fields there and in the posts collection), and these fields should be sufficient:

• title
• last_updated (date field)
• featured_image
• author (this should just be a string field for now, no need for a relation widget or anything like that)
• body

[mradamcox]

Now completed and we have a first example guide up and linked to the homepage as well.