Edit "disabled populations" accordion and remove unused accordions

This MR does a couple of small things:

1. I edited the median rent map to have the land tenure green dimension color, per Oronde's suggestion

2. I added @ancarr's text related to disabled populations as noted in the narrative doc
3. I added new references associated with Mandie's text.

To ensure everything looks good:

git fetch origin
git checkout -b 'edit-dis-accrd' 'origin/edit-dis-accrd'

In terminal:

npm install (if not already installed)
npm run dev 

then navigate to the local host site and preview accordions.

Accordions should look like: