chore: update configuration settings

backend/.env.example

@@ -1,12 +1,7 @@
-# Environment variables declared in this file are automatically made available to Prisma.
-
-DB_URL="postgresql://${DB_USER}:${DB_PASSWORD}@${DB_HOST}/pingvin-share?schema=public"
-DB_USER=postgres
-DB_PASSWORD=postgres
-DB_HOST=localhost:5432
-
+# CONFIGURATION
 APP_URL=http://localhost:3000
 ALLOW_REGISTRATION=true
 MAX_FILE_SIZE=5000000000
 
-JWT_SECRET=csdkdfmfdfdkslfjskl3987rfkhjgdfnkjdf
+# SECURITY
+JWT_SECRET=random-string