fix: .env.example uses incorrect url

Author: chiaryan

apps/frontend/.env.example

@@ -1,4 +1,4 @@
 # URL endpoints of the services
 NEXT_PUBLIC_QUESTION_SERVICE_URL="http://localhost:8080/"
 NEXT_PUBLIC_USER_SERVICE_URL="http://localhost:3001/"
-NEXT_PUBLIC_MATCHING_SERVICE_URL="wss://localhost:8081"
+NEXT_PUBLIC_MATCHING_SERVICE_URL="ws://localhost:8081/match"