fix: post form data

README.md

@@ -82,6 +82,7 @@ func TestCaseDemo(t *testing.T) {
                 AssertEqual("body.json.foo2", 12.3, "check args foo2"),
             hrp.Step("post form data").
                 POST("/post").
+                WithHeaders(map[string]string{"Content-Type": "application/x-www-form-urlencoded; charset=UTF-8"}).
                 WithParams(map[string]interface{}{
                     "foo1": "$varFoo1",       // reference former extracted variable
                     "foo2": "${max($a, $b)}", // 12.3; step level variables are independent, variable b is 3.45 here