update readme

editoast/README.md

@@ -30,12 +30,17 @@ $ curl -f http://localhost:8090/health
 
 ## Tests
 
-To avoid thread conflicts while accessing the database, use the `--test-threads=1` option.
+To avoid thread conflicts while accessing the database, use serial_test
+
+```rust
+#[test]
+#[serial_test::serial]
+```
 
 <!--- TODO: when tests are isolated, allow multiple threads (4 may be a good tradeoff for speed/DB pool)  --->
 
 ```sh
-cargo test -- --test-threads=1
+cargo test
 ```
 
 ## Useful tools