Fix incorrect link/image for Arthur (#520)

diff --git a/landing-pages/site/data/pmc.json b/landing-pages/site/data/pmc.json
index 2a020bc..5c585ae 100644
--- a/landing-pages/site/data/pmc.json
+++ b/landing-pages/site/data/pmc.json
@@ -19,8 +19,8 @@
   },
   {
     "name": "Arthur Wiedmer",
-    "github": "https://github.com/arthwr",
-    "image": "https://github.com/arthwr.png",
+    "github": "https://github.com/artwr",
+    "image": "https://github.com/artwr.png",
     "nick": "arthur"
   },
   {