chore(compose): add comments for lite variant uid/gid configuration in example

compose.example.yml

@@ -29,6 +29,10 @@ services:
     read_only: true
     tmpfs:
       - /app/.next/cache # next image caching
+
+      # for lite variant, do not change uid/gid
+      # - /var/cache/nginx:uid=101,gid=101
+      # - /run:uid=101,gid=101
     security_opt:
       - no-new-privileges:true
     cap_drop: