Update refcache

Author: danielgblanco

static/refcache.json

@@ -4211,6 +4211,10 @@
     "StatusCode": 200,
     "LastSeen": "2024-01-30T16:14:42.076218-05:00"
   },
+  "https://github.com/open-telemetry/sig-end-user": {
+    "StatusCode": 200,
+    "LastSeen": "2024-05-13T17:48:19.136757+01:00"
+  },
   "https://github.com/open-telemetry/sig-security": {
     "StatusCode": 200,
     "LastSeen": "2024-01-30T16:14:36.015951-05:00"