add benchmark doc

Author: astral-data

README.md

@@ -26,7 +26,16 @@ It allows you to map objects to arrays/JSON and **automatically generate OpenAPI
 
 ## Benchmark
 
-![benchmark](./docs/benchmark.png)
+```bash
+    Run vendor/bin/phpbench run benchmarks/ --bootstrap=vendor/autoload.php
+    PHPBench (1.4.1) running benchmarks... #standwithukraine
+    with PHP version 8.4.8, xdebug ❌, opcache ❌
+
+    benchObjectCreation.....................I4 ✔ Mo117.841μs (±3.09%)
+    benchObjectCreationWithoutCache.........I4 ✔ Mo284.568μs (±0.71%)
+    benchObjectToArray......................I4 ✔ Mo62.883μs (±0.56%)
+    benchObjectToArrayWithoutCache..........I4 ✔ Mo211.700μs (±0.84%)
+```
 
 ## Quick Start