Accessibility interactions & touchability for story

[kawilliams]

https://observablehq.com/@d3/multitouch

TODO:

• [x] Confirm mouse events for desktop/laptop
• [ ] Review if mouse events work for touch, and change as necessary

[kawilliams]

• [ ] Make story2.js increment and decrement functions callable via arrow buttons (R arrow, L arrow)
• [ ] If using arrows to navigate, don't make clicking the "predict care cost" label mandatory. Instead, set the variables behind the scenes
• [ ] Same for clicking on the 3 label options

[kawilliams]

Added accessibility interaction options for fig1 via #28