Site updates re: Design Studio

This fairly small MR mainly updates text and alt text for the story, and also includes some illustration and viz updates. The illustrations are updated on s3, including the placeholder dataviz until they are implemented in d3.

[x] trout photo looks like it's copy and pasted in, not styled very similarly to page [x] make trees bigger [x] Alex's sign is confusing [x] Denise looks like she's feeding the fish [x] Could lean into more of a scrapbook style with image of fish [x] remove grid lines on viz [x] make y-axis label/title NYT style [x] use line highlighting to show overlap on one viz of growth versus T, rather than having them stacked (my note: this was what was done with original, which reviewers found confusing. I have some ideas for making it cleaner in NYT style and more readable) [x] Make data viz cleaned up and ready for d3 so Cee can implement those viz in d3