show users reports error if not admin

src/core/system.cpp

@@ -997,6 +997,11 @@ int8_t System::wifi_quality(int8_t dBm) {
 
 // print users to console
 void System::show_users(uuid::console::Shell & shell) {
+    if (!shell.has_flags(CommandFlags::ADMIN)) {
+        shell.printfln("Unauthorized. You need to be an admin to view users.");
+        return;
+    }
+
     shell.printfln("Users:");
 
 #ifndef EMSESP_STANDALONE