Update contribute page image description

Author: Qianqianye

src/content/ui/en.yaml

@@ -58,9 +58,9 @@ contributePage:
   Statement: >
     Our community values contributions of all forms and seeks to expand the meaning of the word contributor as far and wide as possible. It includes documentation, teaching, writing code, making art, writing, design, activism, organizing, curating, or anything else you might imagine.
   ImageAltText: >
-    A group of about 20 people standing and sitting together in front of a doorway with their hands up and happy looks on their faces
+    Group photo of participants smiling enthusiastically with their hands in the air.
   ImageCaption: >
-    TEXT NEEDED HERE
+    Participants of p5.js Contributors Conference 2019.
   DonateDescription: >
     p5.js needs your support!
   # FaqDescription: >