Adding code to render subfolder content as "cards" similar to home page DTT

[krobinsonca]

Description/User story

Add React components to render cards for subfolders on Level 1 page (Delivery Manual, Foundations, etc)

Acceptance Criteria

• Render a card UI for each .md file and folder in the top level folder.
• Card UI mimics the card UI on home: contains a title and body

Design files

[krobinsonca]

As discussed, it will render cards for each .md file and each folder (everything not an index.md) in the top-level folder. Folders and files prefixed with an underscore will be ignored

[amanji]

Is there anything that needs to be modified from the linked PR for this?

[krobinsonca]

@hannahgov - see comment from @amanji