update the alt text for rachel lim img

Author: raclim

src/content/people/en/rachel-lim.yaml

@@ -2,7 +2,7 @@ name: Rachel Lim
 url: https://github.com/raclim
 category: lead
 image: ../images/rachel-lim.jpeg
-imageAlt: WRITE ALT TEXT HERE
+imageAlt: Rachel, a Korean-American woman with medium length black hair smiling as she stands in her backyard.
 role: p5.js Editor Lead, 2022-present
 order: 2
 blurb: >