Adds a missing title to the new switch tile in credentials

lib/steamcmd.dart

@@ -274,6 +274,9 @@ class CredentialsPrompt extends StatelessWidget {
                   ),
                   SwitchListTile(
                       value: z2fa,
+                      title: Text("Enable 2FA"),
+                      subtitle: Text(
+                          "This may or may not be broken... steamcmd is shit!"),
                       onChanged: (value) {
                         z2fa = value;
                       })